MDEV-15751 CURRENT_TIMESTAMP should return a TIMESTAMP [WITH TIME ZONE?]

Changing the return type of the following functions:
  - CURRENT_TIMESTAMP, CURRENT_TIMESTAMP(), NOW()
  - SYSDATE()
  - FROM_UNIXTIME()
from DATETIME to TIMESTAMP.

Note, the old function NOW() returning DATETIME is still available
as LOCALTIMESTAMP or LOCALTIMESTAMP(), e.g.:

  SELECT
    LOCALTIMESTAMP,     -- DATETIME
    CURRENT_TIMESTAMP;  -- TIMESTAMP

The change in the functions return data type fixes some problems
that occurred near a DST change:

- Problem #1

INSERT INTO t1 (timestamp_field) VALUES (CURRENT_TIMESTAMP);
INSERT INTO t1 (timestamp_field) VALUES (COALESCE(CURRENT_TIMESTAMP));

could result into two different values inserted.

- Problem #2

INSERT INTO t1 (timestamp_field) VALUES (FROM_UNIXTIME(1288477526));
INSERT INTO t1 (timestamp_field) VALUES (FROM_UNIXTIME(1288477526+3600));

could result into two equal TIMESTAMP values near a DST change.

Additional changes:

- FROM_UNIXTIME(0) now returns SQL NULL instead of '1970-01-01 00:00:00'
  (assuming time_zone='+00:00')

- UNIX_TIMESTAMP('1970-01-01 00:00:00') now returns SQL NULL instead of 0
  (assuming time_zone='+00:00'

These additional changes are needed for consistency with TIMESTAMP fields,
which cannot store '1970-01-01 00:00:00 +00:00'

mysql-test/main/create.result

@@ -128,7 +128,7 @@ drop table t2;
 create table t2 select now() as a , curtime() as b, curdate() as c , 1+1 as d , 1.0 + 1 as e , 33333333333333333 + 3 as f;
 describe t2;
 Field	Type	Null	Key	Default	Extra
-a	datetime	NO		NULL	
+a	timestamp	NO		NULL	
 b	time	NO		NULL	
 c	date	NO		NULL	
 d	int(3)	NO		NULL	

mysql-test/main/func_group.result

@@ -781,12 +781,12 @@ insert into t1 values (now());
 create table t2 select f2 from (select max(now()) f2 from t1) a;
 show columns from t2;
 Field	Type	Null	Key	Default	Extra
-f2	datetime	YES		NULL	
+f2	timestamp	YES		NULL	
 drop table t2;
 create table t2 select f2 from (select now() f2 from t1) a;
 show columns from t2;
 Field	Type	Null	Key	Default	Extra
-f2	datetime	NO		NULL	
+f2	timestamp	NO		NULL	
 drop table t2, t1;
 CREATE TABLE t1(
 id int PRIMARY KEY,

mysql-test/main/func_time.result

@@ -583,7 +583,9 @@ from_unixtime(2147483647)
 2038-01-19 06:14:07
 select from_unixtime(0);
 from_unixtime(0)
-1970-01-01 03:00:00
+NULL
+Warnings:
+Warning	1292	Truncated incorrect unixtime value: '0.0'
 select unix_timestamp(from_unixtime(2147483647));
 unix_timestamp(from_unixtime(2147483647))
 2147483647
@@ -6323,10 +6325,12 @@ TIME('- 01:00:00')	TIME('- 1 01:00:00')
 SET time_zone='+00:00';
 SELECT NULLIF(FROM_UNIXTIME('foo'), '2012-12-12 21:10:14');
 NULLIF(FROM_UNIXTIME('foo'), '2012-12-12 21:10:14')
-1970-01-01 00:00:00
+NULL
 Warnings:
 Warning	1292	Truncated incorrect DECIMAL value: 'foo'
+Warning	1292	Truncated incorrect unixtime value: '0.0'
 Warning	1292	Truncated incorrect DECIMAL value: 'foo'
+Warning	1292	Truncated incorrect unixtime value: '0.0'
 SET time_zone=DEFAULT;
 #
 # MDEV-18402 Assertion `sec.sec() <= 59' failed in Item_func_maketime::get_date
@@ -6437,3 +6441,120 @@ SET timestamp=DEFAULT;
 #
 # End of 11.6 tests
 #
+#
+# Start of 11.7 tests
+#
+#
+# MDEV-15751 CURRENT_TIMESTAMP should return a TIMESTAMP [WITH TIME ZONE?]
+#
+CREATE TABLE t1 (localtimestamp TIMESTAMP);
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'localtimestamp TIMESTAMP)' at line 1
+CREATE TABLE t1 (current_timestamp TIMESTAMP);
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'current_timestamp TIMESTAMP)' at line 1
+CREATE TABLE t1 AS
+SELECT
+localtimestamp,
+localtimestamp(),
+localtimestamp(0),
+localtimestamp(1),
+localtimestamp(2),
+localtimestamp(3),
+localtimestamp(4),
+localtimestamp(5),
+localtimestamp(6);
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `localtimestamp` datetime NOT NULL,
+  `localtimestamp()` datetime NOT NULL,
+  `localtimestamp(0)` datetime NOT NULL,
+  `localtimestamp(1)` datetime(1) NOT NULL,
+  `localtimestamp(2)` datetime(2) NOT NULL,
+  `localtimestamp(3)` datetime(3) NOT NULL,
+  `localtimestamp(4)` datetime(4) NOT NULL,
+  `localtimestamp(5)` datetime(5) NOT NULL,
+  `localtimestamp(6)` datetime(6) NOT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci
+DROP TABLE t1;
+CREATE TABLE t1 AS
+SELECT
+current_timestamp(),
+current_timestamp(0),
+current_timestamp(1),
+current_timestamp(2),
+current_timestamp(3),
+current_timestamp(4),
+current_timestamp(5),
+current_timestamp(6);
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `current_timestamp()` timestamp NOT NULL,
+  `current_timestamp(0)` timestamp NOT NULL,
+  `current_timestamp(1)` timestamp(1) NOT NULL,
+  `current_timestamp(2)` timestamp(2) NOT NULL,
+  `current_timestamp(3)` timestamp(3) NOT NULL,
+  `current_timestamp(4)` timestamp(4) NOT NULL,
+  `current_timestamp(5)` timestamp(5) NOT NULL,
+  `current_timestamp(6)` timestamp(6) NOT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci
+DROP TABLE t1;
+CREATE TABLE t1 AS
+SELECT
+sysdate(),
+sysdate(0),
+sysdate(1),
+sysdate(2),
+sysdate(3),
+sysdate(4),
+sysdate(5),
+sysdate(6);
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `sysdate()` timestamp NOT NULL,
+  `sysdate(0)` timestamp NOT NULL,
+  `sysdate(1)` timestamp(1) NOT NULL,
+  `sysdate(2)` timestamp(2) NOT NULL,
+  `sysdate(3)` timestamp(3) NOT NULL,
+  `sysdate(4)` timestamp(4) NOT NULL,
+  `sysdate(5)` timestamp(5) NOT NULL,
+  `sysdate(6)` timestamp(6) NOT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci
+DROP TABLE t1;
+CREATE TABLE t1 AS
+SELECT
+from_unixtime(1000000e0),
+from_unixtime(1000000),
+from_unixtime(1000000.1),
+from_unixtime(1000000.12),
+from_unixtime(1000000.123),
+from_unixtime(1000000.1234),
+from_unixtime(1000000.12345),
+from_unixtime(1000000.123456),
+from_unixtime(1000000.1234567),
+from_unixtime(1000000.12345678),
+from_unixtime(1000000.123456789),
+from_unixtime(1000000.1234567891),
+from_unixtime(1000000.12345678912);
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `from_unixtime(1000000e0)` timestamp(6) NULL DEFAULT NULL,
+  `from_unixtime(1000000)` timestamp NULL DEFAULT NULL,
+  `from_unixtime(1000000.1)` timestamp(1) NULL DEFAULT NULL,
+  `from_unixtime(1000000.12)` timestamp(2) NULL DEFAULT NULL,
+  `from_unixtime(1000000.123)` timestamp(3) NULL DEFAULT NULL,
+  `from_unixtime(1000000.1234)` timestamp(4) NULL DEFAULT NULL,
+  `from_unixtime(1000000.12345)` timestamp(5) NULL DEFAULT NULL,
+  `from_unixtime(1000000.123456)` timestamp(6) NULL DEFAULT NULL,
+  `from_unixtime(1000000.1234567)` timestamp(6) NULL DEFAULT NULL,
+  `from_unixtime(1000000.12345678)` timestamp(6) NULL DEFAULT NULL,
+  `from_unixtime(1000000.123456789)` timestamp(6) NULL DEFAULT NULL,
+  `from_unixtime(1000000.1234567891)` timestamp(6) NULL DEFAULT NULL,
+  `from_unixtime(1000000.12345678912)` timestamp(6) NULL DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci
+DROP TABLE t1;
+#
+# End of 11.7 tests
+#

mysql-test/main/func_time.test

@@ -3293,3 +3293,79 @@ SET timestamp=DEFAULT;
 --echo #
 --echo # End of 11.6 tests
 --echo #
+
+--echo #
+--echo # Start of 11.7 tests
+--echo #
+
+--echo #
+--echo # MDEV-15751 CURRENT_TIMESTAMP should return a TIMESTAMP [WITH TIME ZONE?]
+--echo #
+
+--error ER_PARSE_ERROR
+CREATE TABLE t1 (localtimestamp TIMESTAMP);
+--error ER_PARSE_ERROR
+CREATE TABLE t1 (current_timestamp TIMESTAMP);
+
+CREATE TABLE t1 AS
+SELECT
+  localtimestamp,
+  localtimestamp(),
+  localtimestamp(0),
+  localtimestamp(1),
+  localtimestamp(2),
+  localtimestamp(3),
+  localtimestamp(4),
+  localtimestamp(5),
+  localtimestamp(6);
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+
+CREATE TABLE t1 AS
+SELECT
+  current_timestamp(),
+  current_timestamp(0),
+  current_timestamp(1),
+  current_timestamp(2),
+  current_timestamp(3),
+  current_timestamp(4),
+  current_timestamp(5),
+  current_timestamp(6);
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+CREATE TABLE t1 AS
+SELECT
+  sysdate(),
+  sysdate(0),
+  sysdate(1),
+  sysdate(2),
+  sysdate(3),
+  sysdate(4),
+  sysdate(5),
+  sysdate(6);
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+CREATE TABLE t1 AS
+SELECT
+  from_unixtime(1000000e0),
+  from_unixtime(1000000),
+  from_unixtime(1000000.1),
+  from_unixtime(1000000.12),
+  from_unixtime(1000000.123),
+  from_unixtime(1000000.1234),
+  from_unixtime(1000000.12345),
+  from_unixtime(1000000.123456),
+  from_unixtime(1000000.1234567),
+  from_unixtime(1000000.12345678),
+  from_unixtime(1000000.123456789),
+  from_unixtime(1000000.1234567891),
+  from_unixtime(1000000.12345678912);
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+--echo #
+--echo # End of 11.7 tests
+--echo #

mysql-test/main/func_time_hires.result

@@ -39,12 +39,12 @@ t1	CREATE TABLE `t1` (
   `sec_to_time(12345)` time DEFAULT NULL,
   `sec_to_time(12345.6789)` time(4) DEFAULT NULL,
   `sec_to_time(1234567e-2)` time(6) DEFAULT NULL,
-  `now()` datetime NOT NULL,
+  `now()` timestamp NOT NULL,
   `curtime(0)` time NOT NULL,
   `utc_timestamp(1)` datetime(1) NOT NULL,
   `utc_time(2)` time(2) NOT NULL,
   `current_time(3)` time(3) NOT NULL,
-  `current_timestamp(4)` datetime(4) NOT NULL,
+  `current_timestamp(4)` timestamp(4) NOT NULL,
   `localtime(5)` time(5) NOT NULL,
   `localtimestamp(6)` datetime(6) NOT NULL,
   `time_to_sec(123456)` bigint(17) DEFAULT NULL,

mysql-test/main/ps.result

@@ -4574,21 +4574,21 @@ EXECUTE stmt USING CURRENT_TIMESTAMP;
 SHOW CREATE TABLE t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `c1` datetime NOT NULL
+  `c1` timestamp NOT NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
 DROP TABLE t1;
 EXECUTE stmt USING CURRENT_TIMESTAMP(3);
 SHOW CREATE TABLE t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `c1` datetime(3) NOT NULL
+  `c1` timestamp(3) NOT NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
 DROP TABLE t1;
 EXECUTE stmt USING CURRENT_TIMESTAMP(6);
 SHOW CREATE TABLE t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
-  `c1` datetime(6) NOT NULL
+  `c1` timestamp(6) NOT NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
 DROP TABLE t1;
 EXECUTE stmt USING CURRENT_TIME;

mysql-test/main/timezone.result

@@ -53,7 +53,7 @@ DROP TABLE t1;
 select unix_timestamp('1970-01-01 01:00:00'), 
 unix_timestamp('1970-01-01 01:00:01');
 unix_timestamp('1970-01-01 01:00:00')	unix_timestamp('1970-01-01 01:00:01')
-0	1
+NULL	1
 select unix_timestamp('1969-12-31 23:59:59'), unix_timestamp('1970-01-01 00:00:00'), unix_timestamp('1970-01-01 00:59:59');
 unix_timestamp('1969-12-31 23:59:59')	unix_timestamp('1970-01-01 00:00:00')	unix_timestamp('1970-01-01 00:59:59')
 NULL	NULL	NULL

mysql-test/main/timezone2.result

@@ -680,10 +680,10 @@ INSERT INTO t1 VALUES ('2001-01-01 10:20:30'),('2001-01-01 10:20:31');
 # Optimized (more than 24 hours before the DST fall back)
 #
 SET timestamp=@first_second_after_dst_fall_back-24*3600-1;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-UNIX_TIMESTAMP()	NOW()
+UNIX_TIMESTAMP()	LOCALTIMESTAMP()
 1288393199	2010-10-30 02:59:59
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 Warnings:
@@ -692,34 +692,34 @@ Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` =
 # Not optimized (24 hours before the DST fall back)
 #
 SET timestamp=@first_second_after_dst_fall_back-24*3600;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-UNIX_TIMESTAMP()	NOW()
+UNIX_TIMESTAMP()	LOCALTIMESTAMP()
 1288393200	2010-10-30 03:00:00
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 Warnings:
-Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(current_timestamp())
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(localtimestamp())
 #
 # Not optimized (less than 24 hours after the DST fall back)
 #
 SET timestamp=@first_second_after_dst_fall_back+24*3600-1;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-UNIX_TIMESTAMP()	NOW()
+UNIX_TIMESTAMP()	LOCALTIMESTAMP()
 1288565999	2010-11-01 01:59:59
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 Warnings:
-Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(current_timestamp())
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(localtimestamp())
 #
 # Optimized (24 hours after the DST fall back)
 #
 SET timestamp=@first_second_after_dst_fall_back+24*3600;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-UNIX_TIMESTAMP()	NOW()
+UNIX_TIMESTAMP()	LOCALTIMESTAMP()
 1288566000	2010-11-01 02:00:00
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 Warnings:
@@ -737,10 +737,10 @@ INSERT INTO t1 VALUES ('2001-01-01 10:20:30'),('2001-01-01 10:20:31');
 # Optimized (more than 24 hours before the DST sprint forward)
 #
 SET timestamp=@first_second_after_dst_spring_forward-24*3600-1;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-UNIX_TIMESTAMP()	NOW()
+UNIX_TIMESTAMP()	LOCALTIMESTAMP()
 1301093999	2011-03-26 01:59:59
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 Warnings:
@@ -749,34 +749,34 @@ Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` =
 # Not optimized (24 hours before the DST sprint forward)
 #
 SET timestamp=@first_second_after_dst_spring_forward-24*3600;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-UNIX_TIMESTAMP()	NOW()
+UNIX_TIMESTAMP()	LOCALTIMESTAMP()
 1301094000	2011-03-26 02:00:00
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 Warnings:
-Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(current_timestamp())
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(localtimestamp())
 #
 # Not optimized (less than 24 hours after the DST sprint forward)
 #
 SET timestamp=@first_second_after_dst_spring_forward+24*3600-1;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-UNIX_TIMESTAMP()	NOW()
+UNIX_TIMESTAMP()	LOCALTIMESTAMP()
 1301266799	2011-03-28 02:59:59
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 Warnings:
-Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(current_timestamp())
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(localtimestamp())
 #
 # Optimized (24 hours after the DST sprint forward)
 #
 SET timestamp=@first_second_after_dst_spring_forward+24*3600;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-UNIX_TIMESTAMP()	NOW()
+UNIX_TIMESTAMP()	LOCALTIMESTAMP()
 1301266800	2011-03-28 03:00:00
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 Warnings:
@@ -805,10 +805,10 @@ INSERT INTO t1 VALUES ('2001-01-01 10:20:30');
 # Optimized (more than 24 hours before the leap second)
 #
 SET timestamp=@leap_second-24*3600-1;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-UNIX_TIMESTAMP()	NOW()
+UNIX_TIMESTAMP()	LOCALTIMESTAMP()
 362707208	1981-06-30 03:59:59
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	100.00	Using where
 Warnings:
@@ -817,37 +817,79 @@ Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` =
 # Not optimized (24 hours before the leap second)
 #
 SET timestamp=@leap_second-24*3600;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-UNIX_TIMESTAMP()	NOW()
+UNIX_TIMESTAMP()	LOCALTIMESTAMP()
 362707209	1981-06-30 04:00:00
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	100.00	Using where
 Warnings:
-Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(current_timestamp())
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(localtimestamp())
 #
 # Not optimized (less than 24 hours after the leap second)
 #
 SET timestamp=@leap_second+24*3600-1;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-UNIX_TIMESTAMP()	NOW()
+UNIX_TIMESTAMP()	LOCALTIMESTAMP()
 362880008	1981-07-02 03:59:58
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	100.00	Using where
 Warnings:
-Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(current_timestamp())
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(localtimestamp())
 #
 # Not optimized (24 hours after the leap second)
 #
 SET timestamp=@leap_second+24*3600;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-UNIX_TIMESTAMP()	NOW()
+UNIX_TIMESTAMP()	LOCALTIMESTAMP()
 362880009	1981-07-02 03:59:59
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	100.00	Using where
 Warnings:
 Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = TIMESTAMP/*WITH LOCAL TIME ZONE*/'1981-07-02 03:59:59'
 DROP TABLE t1;
 SET time_zone=DEFAULT;
+#
+# End of 11.3 tests
+#
+#
+# Start of 11.7 tests
+#
+#
+# MDEV-15751 CURRENT_TIMESTAMP should return a TIMESTAMP [WITH TIME ZONE?]
+#
+SET time_zone='Europe/Moscow';
+CREATE TABLE t1 (a TIMESTAMP);
+SET timestamp=1288477526 /*summer time*/;
+INSERT INTO t1 VALUES (CURRENT_TIMESTAMP()), (COALESCE(CURRENT_TIMESTAMP()));
+SET timestamp=1288477526+3600 /*winter time*/;
+INSERT INTO t1 VALUES (CURRENT_TIMESTAMP()), (COALESCE(CURRENT_TIMESTAMP()));
+# The two INSERTs produce equal "a" but different UNIX_TIMESTAMP(a)
+SELECT a, UNIX_TIMESTAMP(a) FROM t1;
+a	UNIX_TIMESTAMP(a)
+2010-10-31 02:25:26	1288477526
+2010-10-31 02:25:26	1288477526
+2010-10-31 02:25:26	1288481126
+2010-10-31 02:25:26	1288481126
+DROP TABLE t1;
+SET time_zone=DEFAULT;
+SET time_zone='Europe/Moscow';
+CREATE TABLE t1 (a TIMESTAMP);
+SET timestamp=1288477526 /*summer time*/;
+INSERT INTO t1 VALUES (LOCALTIMESTAMP()), (COALESCE(LOCALTIMESTAMP()));
+SET timestamp=1288477526+3600 /*winter time*/;
+INSERT INTO t1 VALUES (LOCALTIMESTAMP()), (COALESCE(LOCALTIMESTAMP()));
+# The two INSERTs produce equal "a" and equal (summer) UNIX_TIMESTAMP(a)
+SELECT a, UNIX_TIMESTAMP(a) FROM t1;
+a	UNIX_TIMESTAMP(a)
+2010-10-31 02:25:26	1288477526
+2010-10-31 02:25:26	1288477526
+2010-10-31 02:25:26	1288477526
+2010-10-31 02:25:26	1288477526
+DROP TABLE t1;
+SET time_zone=DEFAULT;
+#
+# End of 11.7 tests
+#

mysql-test/main/timezone2.test

@@ -636,32 +636,32 @@ INSERT INTO t1 VALUES ('2001-01-01 10:20:30'),('2001-01-01 10:20:31');
 --echo #
 
 SET timestamp=@first_second_after_dst_fall_back-24*3600-1;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 
 --echo #
 --echo # Not optimized (24 hours before the DST fall back)
 --echo #
 
 SET timestamp=@first_second_after_dst_fall_back-24*3600;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 
 --echo #
 --echo # Not optimized (less than 24 hours after the DST fall back)
 --echo #
 
 SET timestamp=@first_second_after_dst_fall_back+24*3600-1;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 
 --echo #
 --echo # Optimized (24 hours after the DST fall back)
 --echo #
 
 SET timestamp=@first_second_after_dst_fall_back+24*3600;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 
 DROP TABLE t1;
 SET time_zone=DEFAULT;
@@ -684,32 +684,32 @@ INSERT INTO t1 VALUES ('2001-01-01 10:20:30'),('2001-01-01 10:20:31');
 --echo #
 
 SET timestamp=@first_second_after_dst_spring_forward-24*3600-1;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 
 --echo #
 --echo # Not optimized (24 hours before the DST sprint forward)
 --echo #
 
 SET timestamp=@first_second_after_dst_spring_forward-24*3600;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 
 --echo #
 --echo # Not optimized (less than 24 hours after the DST sprint forward)
 --echo #
 
 SET timestamp=@first_second_after_dst_spring_forward+24*3600-1;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 
 --echo #
 --echo # Optimized (24 hours after the DST sprint forward)
 --echo #
 
 SET timestamp=@first_second_after_dst_spring_forward+24*3600;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 
 DROP TABLE t1;
 
@@ -735,33 +735,72 @@ INSERT INTO t1 VALUES ('2001-01-01 10:20:30');
 --echo #
 
 SET timestamp=@leap_second-24*3600-1;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 
 --echo #
 --echo # Not optimized (24 hours before the leap second)
 --echo #
 
 SET timestamp=@leap_second-24*3600;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 
 --echo #
 --echo # Not optimized (less than 24 hours after the leap second)
 --echo #
 
 SET timestamp=@leap_second+24*3600-1;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 
 --echo #
 --echo # Not optimized (24 hours after the leap second)
 --echo #
 
 SET timestamp=@leap_second+24*3600;
-SELECT UNIX_TIMESTAMP(), NOW();
+SELECT UNIX_TIMESTAMP(), LOCALTIMESTAMP();
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=now();
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=LOCALTIMESTAMP();
 
 DROP TABLE t1;
 
 SET time_zone=DEFAULT;
+
+
+--echo #
+--echo # End of 11.3 tests
+--echo #
+
+--echo #
+--echo # Start of 11.7 tests
+--echo #
+
+--echo #
+--echo # MDEV-15751 CURRENT_TIMESTAMP should return a TIMESTAMP [WITH TIME ZONE?]
+--echo #
+
+SET time_zone='Europe/Moscow';
+CREATE TABLE t1 (a TIMESTAMP);
+SET timestamp=1288477526 /*summer time*/;
+INSERT INTO t1 VALUES (CURRENT_TIMESTAMP()), (COALESCE(CURRENT_TIMESTAMP()));
+SET timestamp=1288477526+3600 /*winter time*/;
+INSERT INTO t1 VALUES (CURRENT_TIMESTAMP()), (COALESCE(CURRENT_TIMESTAMP()));
+--echo # The two INSERTs produce equal "a" but different UNIX_TIMESTAMP(a)
+SELECT a, UNIX_TIMESTAMP(a) FROM t1;
+DROP TABLE t1;
+SET time_zone=DEFAULT;
+
+SET time_zone='Europe/Moscow';
+CREATE TABLE t1 (a TIMESTAMP);
+SET timestamp=1288477526 /*summer time*/;
+INSERT INTO t1 VALUES (LOCALTIMESTAMP()), (COALESCE(LOCALTIMESTAMP()));
+SET timestamp=1288477526+3600 /*winter time*/;
+INSERT INTO t1 VALUES (LOCALTIMESTAMP()), (COALESCE(LOCALTIMESTAMP()));
+--echo # The two INSERTs produce equal "a" and equal (summer) UNIX_TIMESTAMP(a)
+SELECT a, UNIX_TIMESTAMP(a) FROM t1;
+DROP TABLE t1;
+SET time_zone=DEFAULT;
+
+--echo #
+--echo # End of 11.7 tests
+--echo #

mysql-test/main/timezone4.result

@@ -1,6 +1,20 @@
 select from_unixtime(0);
 from_unixtime(0)
-1969-12-31 14:00:00
+NULL
+Warnings:
+Warning	1292	Truncated incorrect unixtime value: '0.0'
+select from_unixtime(0.000001);
+from_unixtime(0.000001)
+1969-12-31 14:00:00.000001
+select from_unixtime(1);
+from_unixtime(1)
+1969-12-31 14:00:01
+select unix_timestamp('1969-12-31 14:00:00');
+unix_timestamp('1969-12-31 14:00:00')
+NULL
+select unix_timestamp('1969-12-31 14:00:00.000001');
+unix_timestamp('1969-12-31 14:00:00.000001')
+0.000001
 select unix_timestamp('1969-12-31 14:00:01');
 unix_timestamp('1969-12-31 14:00:01')
 1

mysql-test/main/timezone4.test

@@ -8,6 +8,12 @@
 #
 
 select from_unixtime(0);
+select from_unixtime(0.000001);
+select from_unixtime(1);
+
 # check 0 boundary
+
+select unix_timestamp('1969-12-31 14:00:00');
+select unix_timestamp('1969-12-31 14:00:00.000001');
 select unix_timestamp('1969-12-31 14:00:01');
 

mysql-test/main/type_newdecimal.result

@@ -2472,6 +2472,7 @@ SELECT 1 FROM t1 GROUP BY v1 ORDER BY AVG ( from_unixtime ( '' ) ) ;
 1
 Warnings:
 Warning	1292	Truncated incorrect DECIMAL value: ''
+Warning	1292	Truncated incorrect unixtime value: '0.0'
 DROP TABLE t1;
 SELECT SUM(DISTINCT 0.000000000000000000000000000000000000001);
 SUM(DISTINCT 0.000000000000000000000000000000000000001)

mysql-test/main/type_timestamp,32bit.rdiff

@@ -1,11 +1,6 @@
---- main/type_timestamp.result
+--- type_timestamp.result	2024-09-17 11:32:07.799634536 +0400
-+++ main/type_timestamp.reject
++++ type_timestamp.reject	2024-09-17 14:10:30.223789268 +0400
-@@ -1,4 +1,3 @@
+@@ -1372,7 +1372,7 @@
--drop table if exists t1,t2;
- set time_zone="+03:00";
- CREATE TABLE t1 (a int, t timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP);
- CREATE TABLE t2 (a int, t datetime);
-@@ -1373,7 +1372,7 @@
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
  Warnings:
@@ -14,7 +9,7 @@
  EXPLAIN EXTENDED SELECT * FROM t1 WHERE a='1001-01-01 10:20:30';
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
-@@ -1389,7 +1388,7 @@
+@@ -1388,7 +1388,7 @@
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
  Warnings:
@@ -23,7 +18,7 @@
  EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=10010101102030;
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
-@@ -1404,7 +1403,7 @@
+@@ -1403,7 +1403,7 @@
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
  Warnings:
@@ -32,7 +27,7 @@
  EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=10010101102030e0;
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
-@@ -1419,7 +1418,7 @@
+@@ -1418,7 +1418,7 @@
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
  Warnings:
@@ -41,7 +36,7 @@
  EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=10010101102030.0;
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
-@@ -1434,17 +1433,17 @@
+@@ -1433,17 +1433,17 @@
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
  Warnings:
@@ -62,12 +57,12 @@
  #
  # Comparison predicates: Good TIMESTAMP values switch to TIMESTAMP comparison
  #
-@@ -1570,22 +1569,22 @@
+@@ -1569,22 +1569,22 @@
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
  Warnings:
 -Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = TIMESTAMP/*WITH LOCAL TIME ZONE*/'2038-01-18 03:14:08'
-+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(from_unixtime(0x7fffffff - 24 * 3600 + 1))
++Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(cast(from_unixtime(0x7fffffff - 24 * 3600 + 1) as datetime))
  EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=TIMESTAMP'2038-01-18 03:14:08';
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
@@ -80,16 +75,16 @@
  Warnings:
 -Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = TIMESTAMP/*WITH LOCAL TIME ZONE*/'2038-01-19 03:14:07'
 +Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = TIMESTAMP'2038-01-19 03:14:07'
- EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=FROM_UNIXTIME(0x7FFFFFFF);
+ EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=CAST(FROM_UNIXTIME(0x7FFFFFFF) AS DATETIME);
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
  Warnings:
 -Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = TIMESTAMP/*WITH LOCAL TIME ZONE*/'2038-01-19 03:14:07'
-+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(from_unixtime(0x7fffffff))
++Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = <cache>(cast(from_unixtime(0x7fffffff) as datetime))
  #
  # Corner cases: rounding
  #
-@@ -1620,7 +1619,7 @@
+@@ -1619,7 +1619,7 @@
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
  Warnings:
  Note	1292	Truncated incorrect DATETIME value: '2038-01-18 03:14:07.9999999'
@@ -98,7 +93,7 @@
  SET sql_mode=DEFAULT;
  #
  # NULLIF: Bad TIMESTAMP values preserve DATETIME comparison
-@@ -1639,7 +1638,7 @@
+@@ -1638,7 +1638,7 @@
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
  Warnings:
@@ -107,7 +102,7 @@
  EXPLAIN EXTENDED SELECT * FROM t1 WHERE NULLIF(a,'1001-01-01 10:20:30');
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
-@@ -1654,7 +1653,7 @@
+@@ -1653,7 +1653,7 @@
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
  Warnings:
@@ -116,7 +111,7 @@
  EXPLAIN EXTENDED SELECT * FROM t1 WHERE NULLIF(a,10010101102030);
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
-@@ -1669,7 +1668,7 @@
+@@ -1668,7 +1668,7 @@
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
  Warnings:
@@ -125,7 +120,7 @@
  EXPLAIN EXTENDED SELECT * FROM t1 WHERE NULLIF(a,10010101102030e0);
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
-@@ -1684,7 +1683,7 @@
+@@ -1683,7 +1683,7 @@
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
  Warnings:
@@ -134,7 +129,7 @@
  EXPLAIN EXTENDED SELECT * FROM t1 WHERE NULLIF(a,10010101102030.0);
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
-@@ -1699,7 +1698,7 @@
+@@ -1698,7 +1698,7 @@
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
  1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
  Warnings:

mysql-test/main/type_timestamp.result

@@ -1541,7 +1541,7 @@ Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` =
 # Corner cases: DATETIME values inside the supported optimization range:
 # FROM_UNIXTIME(24*3600) .. FROM_UNIXTIME(0x7FFFFFFF-24*3600)
 #
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=FROM_UNIXTIME(24*3600);
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=CAST(FROM_UNIXTIME(24*3600) AS DATETIME);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
 Warnings:
@@ -1556,7 +1556,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
 Warnings:
 Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = TIMESTAMP/*WITH LOCAL TIME ZONE*/'2038-01-18 03:14:07'
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=FROM_UNIXTIME(0x7FFFFFFF-24*3600);
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=CAST(FROM_UNIXTIME(0x7FFFFFFF-24*3600) AS DATETIME);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
 Warnings:
@@ -1565,7 +1565,7 @@ Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` =
 # Corner cases: DATETIME values after the supported optimization range
 # FROM_UNIXTIME(0x7FFFFFFF-24*3600+1) .. FROM_UNIXTIME(0x7FFFFFFF)
 #
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=FROM_UNIXTIME(0x7FFFFFFF-24*3600+1);
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=CAST(FROM_UNIXTIME(0x7FFFFFFF-24*3600+1) AS DATETIME);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
 Warnings:
@@ -1580,7 +1580,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
 Warnings:
 Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where `test`.`t1`.`a` = TIMESTAMP/*WITH LOCAL TIME ZONE*/'2038-01-19 03:14:07'
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=FROM_UNIXTIME(0x7FFFFFFF);
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=CAST(FROM_UNIXTIME(0x7FFFFFFF) AS DATETIME);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
 Warnings:

mysql-test/main/type_timestamp.test

@@ -992,20 +992,20 @@ EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=FROM_UNIXTIME(24*3600-1);
 --echo # FROM_UNIXTIME(24*3600) .. FROM_UNIXTIME(0x7FFFFFFF-24*3600)
 --echo #
 
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=FROM_UNIXTIME(24*3600);
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=CAST(FROM_UNIXTIME(24*3600) AS DATETIME);
 EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=TIMESTAMP'1970-01-02 00:00:00';
 EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=TIMESTAMP'2038-01-18 03:14:07';
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=FROM_UNIXTIME(0x7FFFFFFF-24*3600);
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=CAST(FROM_UNIXTIME(0x7FFFFFFF-24*3600) AS DATETIME);
 
 --echo #
 --echo # Corner cases: DATETIME values after the supported optimization range
 --echo # FROM_UNIXTIME(0x7FFFFFFF-24*3600+1) .. FROM_UNIXTIME(0x7FFFFFFF)
 --echo #
 
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=FROM_UNIXTIME(0x7FFFFFFF-24*3600+1);
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=CAST(FROM_UNIXTIME(0x7FFFFFFF-24*3600+1) AS DATETIME);
 EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=TIMESTAMP'2038-01-18 03:14:08';
 EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=TIMESTAMP'2038-01-19 03:14:07';
-EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=FROM_UNIXTIME(0x7FFFFFFF);
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=CAST(FROM_UNIXTIME(0x7FFFFFFF) AS DATETIME);
 
 --echo #
 --echo # Corner cases: rounding

mysql-test/suite/binlog/r/type_datetime_func_current_timestamp.result

@@ -0,0 +1,55 @@
+SET time_zone='+02:00';
+SET timestamp=100000000;
+#
+# This test makes sure binlog has SET time_zone
+# for "TIMESTAMP function to DATETIME column" conversion.
+#
+CREATE TABLE t1 (a DATETIME);
+INSERT INTO t1 VALUES (CURRENT_TIMESTAMP());
+INSERT INTO t1 VALUES (COALESCE(CURRENT_TIMESTAMP()));
+DROP TABLE t1;
+FLUSH LOGS;
+/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/;
+/*!40019 SET @@session.max_delayed_threads=0*/;
+/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
+DELIMITER /*!*/;
+ROLLBACK/*!*/;
+use `test`/*!*/;
+SET TIMESTAMP=100000000/*!*/;
+SET @@session.pseudo_thread_id=999999999/*!*/;
+SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=0, @@session.unique_checks=1, @@session.autocommit=1, @@session.check_constraint_checks=1, @@session.sql_if_exists=0, @@session.explicit_defaults_for_timestamp=1, @@session.system_versioning_insert_history=0/*!*/;
+SET @@session.sql_mode=#/*!*/;
+SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/;
+/*!\C latin1 *//*!*/;
+SET @@session.character_set_client=latin1,@@session.collation_connection=8,@@session.collation_server=#/*!*/;
+SET @@session.lc_time_names=0/*!*/;
+SET @@session.collation_database=DEFAULT/*!*/;
+CREATE TABLE t1 (a DATETIME)
+/*!*/;
+START TRANSACTION
+/*!*/;
+SET TIMESTAMP=100000000/*!*/;
+SET @@session.time_zone='+02:00'/*!*/;
+INSERT INTO t1 VALUES (CURRENT_TIMESTAMP())
+/*!*/;
+SET TIMESTAMP=100000000/*!*/;
+COMMIT
+/*!*/;
+START TRANSACTION
+/*!*/;
+SET TIMESTAMP=100000000/*!*/;
+INSERT INTO t1 VALUES (COALESCE(CURRENT_TIMESTAMP()))
+/*!*/;
+SET TIMESTAMP=100000000/*!*/;
+COMMIT
+/*!*/;
+SET TIMESTAMP=100000000/*!*/;
+DROP TABLE `t1` /* generated by server */
+/*!*/;
+DELIMITER ;
+# End of log file
+ROLLBACK /* added by mysqlbinlog */;
+/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
+/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;
+SET time_zone=DEFAULT;
+SET Timestamp=DEFAULT;

mysql-test/suite/binlog/r/type_timestamp_func_current_timestamp.result

@@ -0,0 +1,53 @@
+SET time_zone='+02:00';
+SET timestamp=100000000;
+#
+# This test makes sure binlog does not have SET time_zone
+#
+CREATE TABLE t1 (a TIMESTAMP);
+INSERT INTO t1 VALUES (CURRENT_TIMESTAMP());
+INSERT INTO t1 VALUES (COALESCE(CURRENT_TIMESTAMP()));
+DROP TABLE t1;
+FLUSH LOGS;
+/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/;
+/*!40019 SET @@session.max_delayed_threads=0*/;
+/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
+DELIMITER /*!*/;
+ROLLBACK/*!*/;
+use `test`/*!*/;
+SET TIMESTAMP=100000000/*!*/;
+SET @@session.pseudo_thread_id=999999999/*!*/;
+SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=0, @@session.unique_checks=1, @@session.autocommit=1, @@session.check_constraint_checks=1, @@session.sql_if_exists=0, @@session.explicit_defaults_for_timestamp=1, @@session.system_versioning_insert_history=0/*!*/;
+SET @@session.sql_mode=#/*!*/;
+SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/;
+/*!\C latin1 *//*!*/;
+SET @@session.character_set_client=latin1,@@session.collation_connection=8,@@session.collation_server=#/*!*/;
+SET @@session.lc_time_names=0/*!*/;
+SET @@session.collation_database=DEFAULT/*!*/;
+CREATE TABLE t1 (a TIMESTAMP)
+/*!*/;
+START TRANSACTION
+/*!*/;
+SET TIMESTAMP=100000000/*!*/;
+INSERT INTO t1 VALUES (CURRENT_TIMESTAMP())
+/*!*/;
+SET TIMESTAMP=100000000/*!*/;
+COMMIT
+/*!*/;
+START TRANSACTION
+/*!*/;
+SET TIMESTAMP=100000000/*!*/;
+INSERT INTO t1 VALUES (COALESCE(CURRENT_TIMESTAMP()))
+/*!*/;
+SET TIMESTAMP=100000000/*!*/;
+COMMIT
+/*!*/;
+SET TIMESTAMP=100000000/*!*/;
+DROP TABLE `t1` /* generated by server */
+/*!*/;
+DELIMITER ;
+# End of log file
+ROLLBACK /* added by mysqlbinlog */;
+/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
+/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;
+SET time_zone=DEFAULT;
+SET Timestamp=DEFAULT;

mysql-test/suite/binlog/t/type_datetime_func_current_timestamp.test

@@ -0,0 +1,29 @@
+--source include/not_embedded.inc
+--source include/have_binlog_format_statement.inc
+-- source include/have_log_bin.inc
+
+let $MYSQLD_DATADIR= `select @@datadir`;
+
+--disable_query_log
+reset master; # get rid of previous tests binlog
+--enable_query_log
+
+SET time_zone='+02:00';
+SET timestamp=100000000;
+
+--echo #
+--echo # This test makes sure binlog has SET time_zone
+--echo # for "TIMESTAMP function to DATETIME column" conversion.
+--echo #
+
+CREATE TABLE t1 (a DATETIME);
+INSERT INTO t1 VALUES (CURRENT_TIMESTAMP());
+INSERT INTO t1 VALUES (COALESCE(CURRENT_TIMESTAMP()));
+DROP TABLE t1;
+FLUSH LOGS;
+
+--replace_regex /@@session.sql_mode=\d+/@@session.sql_mode=#/ /collation_server=\d+/collation_server=#/
+--exec $MYSQL_BINLOG $MYSQLD_DATADIR/master-bin.000001 --short-form
+
+SET time_zone=DEFAULT;
+SET Timestamp=DEFAULT;

mysql-test/suite/binlog/t/type_timestamp_func_current_timestamp.test

@@ -0,0 +1,28 @@
+--source include/not_embedded.inc
+--source include/have_binlog_format_statement.inc
+-- source include/have_log_bin.inc
+
+let $MYSQLD_DATADIR= `select @@datadir`;
+
+--disable_query_log
+reset master; # get rid of previous tests binlog
+--enable_query_log
+
+SET time_zone='+02:00';
+SET timestamp=100000000;
+
+--echo #
+--echo # This test makes sure binlog does not have SET time_zone
+--echo #
+
+CREATE TABLE t1 (a TIMESTAMP);
+INSERT INTO t1 VALUES (CURRENT_TIMESTAMP());
+INSERT INTO t1 VALUES (COALESCE(CURRENT_TIMESTAMP()));
+DROP TABLE t1;
+FLUSH LOGS;
+
+--replace_regex /@@session.sql_mode=\d+/@@session.sql_mode=#/ /collation_server=\d+/collation_server=#/
+--exec $MYSQL_BINLOG $MYSQLD_DATADIR/master-bin.000001 --short-form
+
+SET time_zone=DEFAULT;
+SET Timestamp=DEFAULT;

mysql-test/suite/vcol/r/vcol_blocked_sql_funcs.result

@@ -43,9 +43,9 @@ create or replace table t1 (a datetime, b varchar(10) as (localtime) PERSISTENT)
 ERROR HY000: Function or expression 'curtime()' cannot be used in the GENERATED ALWAYS AS clause of `b`
 # LOCALTIMESTAMP, LOCALTIMESTAMP()(v4.0.6)
 create or replace table t1 (a datetime, b varchar(10) as (localtimestamp()) PERSISTENT);
-ERROR HY000: Function or expression 'current_timestamp()' cannot be used in the GENERATED ALWAYS AS clause of `b`
+ERROR HY000: Function or expression 'localtimestamp()' cannot be used in the GENERATED ALWAYS AS clause of `b`
 create or replace table t1 (a datetime, b varchar(10) as (localtimestamp) PERSISTENT);
-ERROR HY000: Function or expression 'current_timestamp()' cannot be used in the GENERATED ALWAYS AS clause of `b`
+ERROR HY000: Function or expression 'localtimestamp()' cannot be used in the GENERATED ALWAYS AS clause of `b`
 # NOW()
 create or replace table t1 (a datetime, b varchar(10) as (now()) PERSISTENT);
 ERROR HY000: Function or expression 'current_timestamp()' cannot be used in the GENERATED ALWAYS AS clause of `b`

mysql-test/suite/versioning/r/derived.result

@@ -211,12 +211,12 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	5	100.00	Using where; Using join buffer (flat, BNL join)
 Query A:
-Note	1003	select `test`.`t1`.`x` AS `x`,`test`.`t1`.`y` AS `y1`,`test`.`t2`.`x` AS `x2`,`test`.`t2`.`y` AS `y2` from `test`.`t1` FOR SYSTEM_TIME AS OF TIMESTAMP current_timestamp(6) join `test`.`t2` FOR SYSTEM_TIME AS OF TIMESTAMP current_timestamp(6) where `test`.`t1`.`x` = `test`.`t2`.`x` and `test`.`t2`.`row_end` > TIMESTAMP/*WITH LOCAL TIME ZONE*/'YYYY-MM-DD hh:ss:mm:.uuuuuu' and `test`.`t2`.`row_start` <= TIMESTAMP/*WITH LOCAL TIME ZONE*/'YYYY-MM-DD hh:ss:mm:.uuuuuu' and `test`.`t1`.`row_end` > TIMESTAMP/*WITH LOCAL TIME ZONE*/'YYYY-MM-DD hh:ss:mm:.uuuuuu' and `test`.`t1`.`row_start` <= TIMESTAMP/*WITH LOCAL TIME ZONE*/'YYYY-MM-DD hh:ss:mm:.uuuuuu'
+Note	1003	select `test`.`t1`.`x` AS `x`,`test`.`t1`.`y` AS `y1`,`test`.`t2`.`x` AS `x2`,`test`.`t2`.`y` AS `y2` from `test`.`t1` FOR SYSTEM_TIME AS OF TIMESTAMP current_timestamp(6) join `test`.`t2` FOR SYSTEM_TIME AS OF TIMESTAMP current_timestamp(6) where `test`.`t1`.`x` = `test`.`t2`.`x` and `test`.`t2`.`row_end` > <cache>(current_timestamp(6)) and `test`.`t2`.`row_start` <= <cache>(current_timestamp(6)) and `test`.`t1`.`row_end` > <cache>(current_timestamp(6)) and `test`.`t1`.`row_start` <= <cache>(current_timestamp(6))
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	5	100.00	Using where; Using join buffer (flat, BNL join)
 Query B:
-Note	1003	select `test`.`t1`.`x` AS `x`,`test`.`t1`.`y` AS `y1`,`test`.`t2`.`x` AS `x2`,`test`.`t2`.`y` AS `y2` from `test`.`t1` FOR SYSTEM_TIME AS OF TIMESTAMP current_timestamp(6) join `test`.`t2` FOR SYSTEM_TIME AS OF TIMESTAMP current_timestamp(6) where `test`.`t1`.`x` = `test`.`t2`.`x` and `test`.`t2`.`row_end` > TIMESTAMP/*WITH LOCAL TIME ZONE*/'YYYY-MM-DD hh:ss:mm:.uuuuuu' and `test`.`t2`.`row_start` <= TIMESTAMP/*WITH LOCAL TIME ZONE*/'YYYY-MM-DD hh:ss:mm:.uuuuuu' and `test`.`t1`.`row_end` > TIMESTAMP/*WITH LOCAL TIME ZONE*/'YYYY-MM-DD hh:ss:mm:.uuuuuu' and `test`.`t1`.`row_start` <= TIMESTAMP/*WITH LOCAL TIME ZONE*/'YYYY-MM-DD hh:ss:mm:.uuuuuu'
+Note	1003	select `test`.`t1`.`x` AS `x`,`test`.`t1`.`y` AS `y1`,`test`.`t2`.`x` AS `x2`,`test`.`t2`.`y` AS `y2` from `test`.`t1` FOR SYSTEM_TIME AS OF TIMESTAMP current_timestamp(6) join `test`.`t2` FOR SYSTEM_TIME AS OF TIMESTAMP current_timestamp(6) where `test`.`t1`.`x` = `test`.`t2`.`x` and `test`.`t2`.`row_end` > <cache>(current_timestamp(6)) and `test`.`t2`.`row_start` <= <cache>(current_timestamp(6)) and `test`.`t1`.`row_end` > <cache>(current_timestamp(6)) and `test`.`t1`.`row_start` <= <cache>(current_timestamp(6))
 Fine result: queries A and B are equal.
 ## LEFT JOIN: t1, t2 versioned
 select * from (

sql/field.h

@@ -3272,7 +3272,7 @@ public:
   bool zero_pack() const override { return false; }
   /*
     This method is used by storage/perfschema and
-    Item_func_now_local::save_in_field().
+    thd_get_query_start_data().
   */
   void store_TIME(my_time_t ts, ulong sec_part)
   {

sql/item.cc

@@ -2752,6 +2752,26 @@ bool Type_std_attributes::agg_item_set_converter(const DTCollation &coll,
 }
 
 
+bool
+Item_func_or_sum
+ ::check_fsp_or_error() const
+{
+  if (decimals > TIME_SECOND_PART_DIGITS)
+  {
+    /*
+      Historically MariaDB raises ER_TOO_BIG_PRECISION
+      instead of ER_TOO_BIG_SCALE when checking fractional digits
+      of an SQL function. Perhaps should be fixed eventually.
+    */
+    my_error(ER_TOO_BIG_PRECISION, MYF(0),
+             func_name(), TIME_SECOND_PART_DIGITS);
+    return true;
+  }
+  return false;
+}
+
+
+
 /**
   @brief
     Building clone for Item_func_or_sum

sql/item.h

@@ -5601,6 +5601,8 @@ class Item_func_or_sum: public Item_result_field,
                         public Used_tables_and_const_cache
 {
 protected:
+  bool check_fsp_or_error() const;
+
   bool agg_arg_charsets(DTCollation &c, Item **items, uint nitems,
                         uint flags, int item_sep)
   {

sql/item_timefunc.cc

@@ -1255,6 +1255,15 @@ bool Item_func_unix_timestamp::get_timestamp_value(my_time_t *seconds,
   Timestamp tm(native);
   *seconds= (my_time_t) tm.tv_sec;
   *second_part= tm.tv_usec;
+  if ((null_value= (tm.tv_sec == 0 && tm.tv_usec == 0)))
+  {
+    /*
+      The value {0,0}='1970-01-01 00:00:00.000000 GMT' cannot be
+      stored in a TIMESTAMP field. Return SQL NULL.
+      Simmetrically, UNIX_TIMESTAMP(0) also returns SQL NULL.
+    */
+    return true;
+  }
   return false;
 }
 
@@ -1536,6 +1545,17 @@ bool Item_func_from_days::get_date(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzz
 }
 
 
+bool Item_func_current_timestamp::val_native(THD *thd, Native *to)
+{
+  Timestamp ts(Timeval(thd->query_start(), thd->query_start_sec_part()));
+  /*
+    to_native() can fail in case of EOM. Don't set null_value on EOM,
+    because CURRENT_TIMESTAMP is NOT NULL. The statement will fail anyway.
+  */
+  return ts.trunc(decimals).to_native(to, decimals);
+}
+
+
 /**
     Converts current time in my_time_t to MYSQL_TIME representation for local
     time zone. Defines time zone (local) used for whole CURDATE function.
@@ -1581,13 +1601,8 @@ bool Item_func_curdate::get_date(THD *thd, MYSQL_TIME *res,
 
 bool Item_func_curtime::fix_fields(THD *thd, Item **items)
 {
-  if (decimals > TIME_SECOND_PART_DIGITS)
+  return check_fsp_or_error() ||
-  {
+         Item_timefunc::fix_fields(thd, items);
-    my_error(ER_TOO_BIG_PRECISION, MYF(0),
-             func_name(), TIME_SECOND_PART_DIGITS);
-    return 1;
-  }
-  return Item_timefunc::fix_fields(thd, items);
 }
 
 bool Item_func_curtime::get_date(THD *thd, MYSQL_TIME *res,
@@ -1657,13 +1672,8 @@ void Item_func_curtime_utc::store_now_in_TIME(THD *thd, MYSQL_TIME *now_time)
 
 bool Item_func_now::fix_fields(THD *thd, Item **items)
 {
-  if (decimals > TIME_SECOND_PART_DIGITS)
+  return check_fsp_or_error() ||
-  {
+         Item_datetimefunc::fix_fields(thd, items);
-    my_error(ER_TOO_BIG_PRECISION, MYF(0),
-             func_name(), TIME_SECOND_PART_DIGITS);
-    return 1;
-  }
-  return Item_datetimefunc::fix_fields(thd, items);
 }
 
 void Item_func_now::print(String *str, enum_query_type query_type)
@@ -1676,23 +1686,6 @@ void Item_func_now::print(String *str, enum_query_type query_type)
 }
 
 
-int Item_func_now_local::save_in_field(Field *field, bool no_conversions)
-{
-  if (field->type() == MYSQL_TYPE_TIMESTAMP)
-  {
-    THD *thd= field->get_thd();
-    my_time_t ts= thd->query_start();
-    ulong sec_part= decimals ? thd->query_start_sec_part() : 0;
-    sec_part-= my_time_fraction_remainder(sec_part, decimals);
-    field->set_notnull();
-    field->store_timestamp(ts, sec_part);
-    return 0;
-  }
-  else
-    return Item_datetimefunc::save_in_field(field, no_conversions);
-}
-
-
 /**
     Converts current time in my_time_t to MYSQL_TIME representation for local
     time zone. Defines time zone (local) used for whole NOW function.
@@ -1739,22 +1732,18 @@ bool Item_func_now::get_date(THD *thd, MYSQL_TIME *res,
     Converts current time in my_time_t to MYSQL_TIME representation for local
     time zone. Defines time zone (local) used for whole SYSDATE function.
 */
-void Item_func_sysdate_local::store_now_in_TIME(THD *thd, MYSQL_TIME *now_time)
+bool Item_func_sysdate_local::val_native(THD *thd, Native *to)
 {
   my_hrtime_t now= my_hrtime();
-  thd->variables.time_zone->gmt_sec_to_TIME(now_time, hrtime_to_my_time(now));
+  Timestamp ts(hrtime_to_my_time(now), hrtime_sec_part(now));
-  set_sec_part(hrtime_sec_part(now), now_time, this);
+  /*
-  thd->used|= THD::TIME_ZONE_USED;
+    to_native() can fail on EOM. Don't set null_value here,
+    because SYSDATE is NOT NULL. The statement will fail anyway.
+  */
+  return ts.trunc(decimals).to_native(to, decimals);
 }
 
 
-bool Item_func_sysdate_local::get_date(THD *thd, MYSQL_TIME *res,
-                                       date_mode_t fuzzydate __attribute__((unused)))
-{
-  store_now_in_TIME(thd, res);
-  return 0;
-}
-
 bool Item_func_sec_to_time::get_date(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzzydate)
 {
   DBUG_ASSERT(fixed());
@@ -2766,7 +2755,6 @@ null_date:
 
 bool Item_func_from_unixtime::fix_length_and_dec(THD *thd)
 {
-  thd->used|= THD::TIME_ZONE_USED;
   tz= thd->variables.time_zone;
   Type_std_attributes::set(
     Type_temporal_attributes_not_fixed_dec(MAX_DATETIME_WIDTH,
@@ -2777,26 +2765,36 @@ bool Item_func_from_unixtime::fix_length_and_dec(THD *thd)
 }
 
 
-bool Item_func_from_unixtime::get_date(THD *thd, MYSQL_TIME *ltime,
+bool Item_func_from_unixtime::val_native(THD *thd, Native *to)
-				       date_mode_t fuzzydate __attribute__((unused)))
 {
-  bzero((char *)ltime, sizeof(*ltime));
-  ltime->time_type= MYSQL_TIMESTAMP_TIME;
-
   VSec9 sec(thd, args[0], "unixtime", TIMESTAMP_MAX_VALUE);
   DBUG_ASSERT(sec.is_null() || sec.sec() <= TIMESTAMP_MAX_VALUE);
 
   if (sec.is_null() || sec.truncated() || sec.neg())
     return (null_value= 1);
 
-  sec.round(MY_MIN(decimals, TIME_SECOND_PART_DIGITS), thd->temporal_round_mode());
+  // decimals can be NOT_FIXED_DEC
+  decimal_digits_t fixed_decimals= MY_MIN(decimals, TIME_SECOND_PART_DIGITS);
+
+  sec.round(fixed_decimals, thd->temporal_round_mode());
+
+  if (sec.sec() == 0 && sec.usec() == 0)
+  {
+    /*
+      The value {0,0}='1970-01-01 00:00:00.000000 GMT' cannot be
+      stored in a TIMESTAMP field. Return SQL NULL.
+      Simmetrically, UNIX_TIMESTAMP('1970-01-01 00:00:00')
+      also returns SQL NULL (assuming time_zone='+00:00').
+    */
+    thd->push_warning_truncated_wrong_value("unixtime", "0.0");
+    return (null_value= true); // 0.0 after rounding
+  }
+
   if (sec.sec() > TIMESTAMP_MAX_VALUE)
     return (null_value= true); // Went out of range after rounding
 
-  tz->gmt_sec_to_TIME(ltime, (my_time_t) sec.sec());
+  const Timestamp ts(Timeval(sec.sec(), sec.usec()));
-  ltime->second_part= sec.usec();
+  return null_value= ts.to_native(to, fixed_decimals);
-
-  return (null_value= 0);
 }
 
 

sql/item_timefunc.h

@@ -708,6 +708,50 @@ public:
 };
 
 
+class Item_timestampfunc: public Item_func
+{
+protected:
+  Datetime to_datetime(THD *thd)
+  {
+    return Timestamp_or_zero_datetime_native_null(thd, this).to_datetime(thd);
+  }
+public:
+  Item_timestampfunc(THD *thd) :Item_func(thd) {}
+  Item_timestampfunc(THD *thd, uint dec) :Item_func(thd) { decimals= dec; }
+  Item_timestampfunc(THD *thd, Item *a) :Item_func(thd, a) {}
+  const Type_handler *type_handler() const override
+  { return &type_handler_timestamp2; }
+  bool get_date(THD *thd, MYSQL_TIME *ltime, date_mode_t fuzzydate) override
+  {
+    return null_value= to_datetime(thd).copy_to_mysql_time(ltime);
+  }
+  double val_real() override
+  {
+    const Datetime dt= to_datetime(current_thd);
+    null_value= !dt.is_valid_datetime();
+    return dt.to_double();
+  }
+  longlong val_int() override
+  {
+    const Datetime dt= to_datetime(current_thd);
+    null_value= !dt.is_valid_datetime();
+    return dt.to_longlong();
+  }
+  my_decimal *val_decimal(my_decimal *to) override
+  {
+    const Datetime dt= to_datetime(current_thd);
+    null_value= !dt.is_valid_datetime();
+    return dt.to_decimal(to);
+  }
+  String *val_str(String *to) override
+  {
+    const Datetime dt= to_datetime(current_thd);
+    null_value= !dt.is_valid_datetime();
+    return dt.to_string(to, decimals);
+  }
+};
+
+
 /* Abstract CURTIME function. Children should define what time zone is used */
 
 class Item_func_curtime :public Item_timefunc
@@ -838,18 +882,53 @@ public:
 };
 
 
+class Item_func_current_timestamp: public Item_timestampfunc
+{
+public:
+  Item_func_current_timestamp(THD *thd, uint dec)
+   :Item_timestampfunc(thd, dec)
+  { }
+  LEX_CSTRING func_name_cstring() const override
+  {
+    static LEX_CSTRING name= {STRING_WITH_LEN("current_timestamp") };
+    return name;
+  }
+  void print(String *str, enum_query_type query_type) override
+  {
+    str->append(func_name_cstring());
+    str->append('(');
+    if (decimals)
+      str->append_ulonglong(decimals);
+    str->append(')');
+  }
+  bool fix_length_and_dec(THD *thd) override
+  {
+    if (check_fsp_or_error())
+      return true;
+    fix_attributes_datetime(decimals);
+    return false;
+  }
+  bool val_native(THD *thd, Native *to) override;
+  bool check_vcol_func_processor(void *arg) override
+  {
+    return mark_unsupported_function(func_name(), "()", arg, VCOL_TIME_FUNC);
+  }
+  enum Functype functype() const override { return NOW_FUNC; }
+  Item *do_get_copy(THD *thd) const override
+  { return get_item_copy<Item_func_current_timestamp>(thd, this); }
+};
+
+
 class Item_func_now_local :public Item_func_now
 {
 public:
   Item_func_now_local(THD *thd, uint dec): Item_func_now(thd, dec) {}
   LEX_CSTRING func_name_cstring() const override
   {
-    static LEX_CSTRING name= {STRING_WITH_LEN("current_timestamp") };
+    static LEX_CSTRING name= {STRING_WITH_LEN("localtimestamp") };
     return name;
   }
-  int save_in_field(Field *field, bool no_conversions) override;
   void store_now_in_TIME(THD *thd, MYSQL_TIME *now_time) override;
-  enum Functype functype() const override { return NOW_FUNC; }
   Item *do_get_copy(THD *thd) const override
   { return get_item_copy<Item_func_now_local>(thd, this); }
 };
@@ -880,18 +959,34 @@ public:
   This is like NOW(), but always uses the real current time, not the
   query_start(). This matches the Oracle behavior.
 */
-class Item_func_sysdate_local :public Item_func_now
+class Item_func_sysdate_local :public Item_timestampfunc
 {
 public:
-  Item_func_sysdate_local(THD *thd, uint dec): Item_func_now(thd, dec) {}
+  Item_func_sysdate_local(THD *thd, uint dec)
+   :Item_timestampfunc(thd, dec)
+  { }
   bool const_item() const override { return 0; }
   LEX_CSTRING func_name_cstring() const override
   {
     static LEX_CSTRING name= {STRING_WITH_LEN("sysdate") };
     return name;
   }
-  void store_now_in_TIME(THD *thd, MYSQL_TIME *now_time) override;
+  void print(String *str, enum_query_type query_type) override
-  bool get_date(THD *thd, MYSQL_TIME *res, date_mode_t fuzzydate) override;
+  {
+    str->append(func_name_cstring());
+    str->append('(');
+    if (decimals)
+      str->append_ulonglong(decimals);
+    str->append(')');
+  }
+  bool fix_length_and_dec(THD *thd) override
+  {
+    if (check_fsp_or_error())
+      return true;
+    fix_attributes_datetime(decimals);
+    return false;
+  }
+  bool val_native(THD *thd, Native *to) override;
   table_map used_tables() const override { return RAND_TABLE_BIT; }
   bool check_vcol_func_processor(void *arg) override
   {
@@ -1033,20 +1128,20 @@ public:
 };
 
 
-class Item_func_from_unixtime :public Item_datetimefunc
+class Item_func_from_unixtime :public Item_timestampfunc
 {
   bool check_arguments() const override
   { return args[0]->check_type_can_return_decimal(func_name_cstring()); }
   Time_zone *tz;
  public:
-  Item_func_from_unixtime(THD *thd, Item *a): Item_datetimefunc(thd, a) {}
+  Item_func_from_unixtime(THD *thd, Item *a): Item_timestampfunc(thd, a) {}
   LEX_CSTRING func_name_cstring() const override
   {
     static LEX_CSTRING name= {STRING_WITH_LEN("from_unixtime") };
     return name;
   }
   bool fix_length_and_dec(THD *thd) override;
-  bool get_date(THD *thd, MYSQL_TIME *res, date_mode_t fuzzydate) override;
+  bool val_native(THD *thd, Native *to) override;
   bool check_vcol_func_processor(void *arg) override
   {
     return mark_unsupported_function(func_name(), "()", arg, VCOL_SESSION_FUNC);

sql/lex.h

@@ -353,7 +353,7 @@ SYMBOL symbols[] = {
   { "LOAD",		SYM(LOAD)},
   { "LOCAL",		SYM(LOCAL_SYM)},
   { "LOCALTIME",	SYM(CURTIME)},
-  { "LOCALTIMESTAMP",	SYM(NOW_SYM)},
+  { "LOCALTIMESTAMP",	SYM(LOCALTIMESTAMP)},
   { "LOCK",		SYM(LOCK_SYM)},
   { "LOCKED",		SYM(LOCKED_SYM)},
   { "LOCKS",		SYM(LOCKS_SYM)},

sql/sql_lex.cc

@@ -9613,7 +9613,7 @@ Item *LEX::make_item_func_sysdate(THD *thd, uint fsp)
   set_stmt_unsafe(LEX::BINLOG_STMT_UNSAFE_SYSTEM_FUNCTION);
   Item *item= global_system_variables.sysdate_is_now == 0 ?
               (Item *) new (thd->mem_root) Item_func_sysdate_local(thd, fsp) :
-              (Item *) new (thd->mem_root) Item_func_now_local(thd, fsp);
+              (Item *) new (thd->mem_root) Item_func_current_timestamp(thd, fsp);
   if (unlikely(item == NULL))
     return NULL;
   safe_to_cache_query=0;

sql/sql_type.cc

@@ -468,7 +468,10 @@ bool Timestamp::to_native(Native *to, uint decimals) const
 {
   uint len= my_timestamp_binary_length(decimals);
   if (to->reserve(len))
+  {
+    to->length(0); // Safety: set to '0000-00-00 00:00:00' on falures
     return true;
+  }
   my_timestamp_to_binary(this, (uchar *) to->ptr(), decimals);
   to->length(len);
   return false;

sql/sql_type.h

@@ -1340,7 +1340,7 @@ public:
   {
     return is_valid_temporal() ? TIME_to_double(this) : 0;
   }
-  my_decimal *to_decimal(my_decimal *to)
+  my_decimal *to_decimal(my_decimal *to) const
   {
     return is_valid_temporal() ? Temporal::to_decimal(to) : bad_to_decimal(to);
   }
@@ -1987,7 +1987,7 @@ public:
       str->length(my_time_to_str(this, const_cast<char*>(str->ptr()), dec));
     return str;
   }
-  my_decimal *to_decimal(my_decimal *to)
+  my_decimal *to_decimal(my_decimal *to) const
   {
     return is_valid_time() ? Temporal::to_decimal(to) : bad_to_decimal(to);
   }
@@ -2342,7 +2342,7 @@ public:
       str->length(my_date_to_str(this, const_cast<char*>(str->ptr())));
     return str;
   }
-  my_decimal *to_decimal(my_decimal *to)
+  my_decimal *to_decimal(my_decimal *to) const
   {
     return is_valid_date() ? Temporal::to_decimal(to) : bad_to_decimal(to);
   }
@@ -2663,7 +2663,7 @@ public:
       str->length(my_datetime_to_str(this, const_cast<char*>(str->ptr()), dec));
     return str;
   }
-  my_decimal *to_decimal(my_decimal *to)
+  my_decimal *to_decimal(my_decimal *to) const
   {
     return is_valid_datetime() ? Temporal::to_decimal(to) : bad_to_decimal(to);
   }

sql/sql_yacc.yy

@@ -572,6 +572,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
 %token  <kwd> LINEAR_SYM
 %token  <kwd> LINES
 %token  <kwd> LOAD
+%token  <kwd> LOCALTIMESTAMP                /* SQL-2003-R */
 %token  <kwd> LOCATOR_SYM                   /* SQL-2003-N */
 %token  <kwd> LOCK_SYM
 %token  <kwd> LONGBLOB
@@ -3097,7 +3098,7 @@ opt_ev_status:
 ev_starts:
           /* empty */
           {
-            Item *item= new (thd->mem_root) Item_func_now_local(thd, 0);
+            Item *item= new (thd->mem_root) Item_func_current_timestamp(thd, 0);
             if (unlikely(item == NULL))
               MYSQL_YYABORT;
             Lex->event_parse_data->item_starts= item;
@@ -6678,7 +6679,7 @@ attribute:
           }
         | ON UPDATE_SYM NOW_SYM opt_default_time_precision
           {
-            Item *item= new (thd->mem_root) Item_func_now_local(thd, $4);
+            Item *item= new (thd->mem_root) Item_func_current_timestamp(thd, $4);
             if (unlikely(item == NULL))
               MYSQL_YYABORT;
             Lex->last_field->on_update= item;
@@ -10500,9 +10501,16 @@ function_call_nonkeyword:
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | NOW_SYM opt_time_precision
+        | LOCALTIMESTAMP opt_time_precision
           {
             $$= new (thd->mem_root) Item_func_now_local(thd, $2);
+            if (unlikely($$ == NULL))
+              MYSQL_YYABORT;
+            Lex->safe_to_cache_query= false;
+          }
+        | NOW_SYM opt_time_precision
+          {
+            $$= new (thd->mem_root) Item_func_current_timestamp(thd, $2);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
             Lex->safe_to_cache_query=0;