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The problem in this bug is when we create temporary tables. When temporary tables are created for unions, there is some inferrence being carried out regarding the type of the column. Whenever this column type is inferred to be REAL (i.e. FLOAT or DOUBLE), MySQL will always try to maintain exact precision, and if that is not possible (there are hardware limits, since FLOAT and DOUBLE are stored as approximate values) will switch to using approximate values. The problem here is that at this point the information about number of significant digits is not available. Furthermore, the number of significant digits should be increased for the AVG function, however, this was not properly handled. There are 4 parts to the problem: #1: DOUBLE and FLOAT fields don't display their proper display lengths in max_display_length(). This is hard-coded as 53 for DOUBLE and 24 for FLOAT. Now changed to instead return the field_length. #2: Type holders for temporary tables do not preserve the max_length of the Item's from which they are created, and is instead reverted to the 53 and 24 from above. This causes *all* fields to get non-fixed significant digits. #3: AVG function does not update max_length (display length) when updating number of decimals. #4: The function that switches to non-fixed number of significant digits should use DBL_DIG + 2 or FLT_DIG + 2 as cut-off values (Since fixed precision does not use the 'e' notation) Of these points, #1 is the controversial one, but this change is preferred and has been cleared with Monty. The function causes quite a few unit tests to blow up and they had to b changed, but each one is annotated and motivated. We frequently see the magical 53 and 24 give way to more relevant numbers. mysql-test/r/create.result: bug#24791 changed test result With the changes made for FLOAT and DOUBLE, the original display lengths are now preserved. mysql-test/r/temp_table.result: bug#24791 changed test resullt Test case added mysql-test/r/type_float.result: bug#24791 changed test result delta 1: field was originally declared as DOUBLE with no display length, so the hardware maximum is chosen rather than 53. delta 2: fields exceed the maximum precision and thus switch to non-fixed significant digits delta 3: Same as above, number of decmals and significant digits was not specified when t3 was created. mysql-test/t/temp_table.test: bug#24791 Test case sql/field.h: bug#24791 The method max_display_length is reimplemented as uint32 max_display_length() { return field_length; } in Field_double and Field_float. Since all subclasses of Field_real now have the same implementation of this method, the implementation has been moved up the hierarchy to Field_real. sql/item.cc: bug#24791 We switch to a non-fixed number of significant digits (by setting decimals=NOT_FIXED_DECIMAL) if the calculated display length is greater than the display length of a value with the maximum precision. These values differ for double and float, obviously. sql/item_sum.cc: bug#24791 We must increase the display length accordinly whenever we change number of decimal places.
175 lines
4.8 KiB
Text
175 lines
4.8 KiB
Text
drop table if exists t1,t2;
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drop view if exists v1;
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CREATE TABLE t1 (c int not null, d char (10) not null);
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insert into t1 values(1,""),(2,"a"),(3,"b");
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CREATE TEMPORARY TABLE t1 (a int not null, b char (10) not null);
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insert into t1 values(4,"e"),(5,"f"),(6,"g");
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alter table t1 rename t2;
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select * from t1;
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c d
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1
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2 a
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3 b
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select * from t2;
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a b
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4 e
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5 f
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6 g
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CREATE TABLE t2 (x int not null, y int not null);
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alter table t2 rename t1;
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select * from t1;
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a b
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4 e
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5 f
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6 g
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create TEMPORARY TABLE t2 engine=heap select * from t1;
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create TEMPORARY TABLE IF NOT EXISTS t2 (a int) engine=heap;
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Warnings:
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Note 1050 Table 't2' already exists
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CREATE TEMPORARY TABLE t1 (a int not null, b char (10) not null);
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ERROR 42S01: Table 't1' already exists
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ALTER TABLE t1 RENAME t2;
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ERROR 42S01: Table 't2' already exists
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select * from t2;
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a b
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4 e
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5 f
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6 g
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alter table t2 add primary key (a,b);
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drop table t1,t2;
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select * from t1;
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c d
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1
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2 a
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3 b
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drop table t2;
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create temporary table t1 select *,2 as "e" from t1;
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select * from t1;
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c d e
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1 2
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2 a 2
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3 b 2
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drop table t1;
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drop table t1;
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CREATE TABLE t1 (pkCrash INTEGER PRIMARY KEY,strCrash VARCHAR(255));
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INSERT INTO t1 ( pkCrash, strCrash ) VALUES ( 1, '1');
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SELECT CONCAT_WS(pkCrash, strCrash) FROM t1;
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CONCAT_WS(pkCrash, strCrash)
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1
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drop table t1;
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create temporary table t1 select 1 as 'x';
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drop table t1;
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CREATE TABLE t1 (x INT);
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INSERT INTO t1 VALUES (1), (2), (3);
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CREATE TEMPORARY TABLE tmp SELECT *, NULL FROM t1;
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drop table t1;
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create temporary table t1 (id int(10) not null unique);
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create temporary table t2 (id int(10) not null primary key,
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val int(10) not null);
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insert into t1 values (1),(2),(4);
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insert into t2 values (1,1),(2,1),(3,1),(4,2);
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select one.id, two.val, elt(two.val,'one','two') from t1 one, t2 two where two.id=one.id order by one.id;
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id val elt(two.val,'one','two')
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1 1 one
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2 1 one
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4 2 two
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drop table t1,t2;
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create temporary table t1 (a int not null);
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insert into t1 values (1),(1);
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alter table t1 add primary key (a);
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ERROR 23000: Duplicate entry '1' for key 1
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drop table t1;
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CREATE TABLE t1 (
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d datetime default NULL
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) ENGINE=MyISAM;
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INSERT INTO t1 VALUES ('2002-10-24 14:50:32'),('2002-10-24 14:50:33'),('2002-10-24 14:50:34'),('2002-10-24 14:50:34'),('2002-10-24 14:50:34'),('2002-10-24 14:50:35'),('2002-10-24 14:50:35'),('2002-10-24 14:50:35'),('2002-10-24 14:50:35'),('2002-10-24 14:50:36'),('2002-10-24 14:50:36'),('2002-10-24 14:50:36'),('2002-10-24 14:50:36'),('2002-10-24 14:50:37'),('2002-10-24 14:50:37'),('2002-10-24 14:50:37'),('2002-10-24 14:50:37'),('2002-10-24 14:50:38'),('2002-10-24 14:50:38'),('2002-10-24 14:50:38'),('2002-10-24 14:50:39'),('2002-10-24 14:50:39'),('2002-10-24 14:50:39'),('2002-10-24 14:50:39'),('2002-10-24 14:50:40'),('2002-10-24 14:50:40'),('2002-10-24 14:50:40');
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flush status;
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select * from t1 group by d;
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d
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2002-10-24 14:50:32
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2002-10-24 14:50:33
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2002-10-24 14:50:34
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2002-10-24 14:50:35
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2002-10-24 14:50:36
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2002-10-24 14:50:37
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2002-10-24 14:50:38
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2002-10-24 14:50:39
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2002-10-24 14:50:40
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show status like "created_tmp%tables";
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Variable_name Value
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Created_tmp_disk_tables 0
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Created_tmp_tables 2
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drop table t1;
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create temporary table v1 as select 'This is temp. table' A;
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create view v1 as select 'This is view' A;
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select * from v1;
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A
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This is temp. table
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show create table v1;
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Table Create Table
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v1 CREATE TEMPORARY TABLE `v1` (
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`A` varchar(19) NOT NULL default ''
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) ENGINE=MyISAM DEFAULT CHARSET=latin1
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show create view v1;
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View Create View
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v1 CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v1` AS select _latin1'This is view' AS `A`
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drop view v1;
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select * from v1;
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A
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This is temp. table
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create view v1 as select 'This is view again' A;
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select * from v1;
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A
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This is temp. table
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drop table v1;
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select * from v1;
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A
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This is view again
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drop view v1;
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create table t1 (a int, b int, index(a), index(b));
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create table t2 (c int auto_increment, d varchar(255), primary key (c));
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insert into t1 values (3,1),(3,2);
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insert into t2 values (NULL, 'foo'), (NULL, 'bar');
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select d, c from t1 left join t2 on b = c where a = 3 order by d;
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d c
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bar 2
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foo 1
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drop table t1, t2;
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DROP TABLE IF EXISTS t1;
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CREATE TABLE t1 (i INT);
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LOCK TABLE t1 WRITE;
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CREATE TEMPORARY TABLE t1 (i INT);
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The following command should not block
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DROP TEMPORARY TABLE t1;
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DROP TABLE t1;
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CREATE TABLE t1 (i INT);
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CREATE TEMPORARY TABLE t2 (i INT);
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DROP TEMPORARY TABLE t2, t1;
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ERROR 42S02: Unknown table 't1'
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SELECT * FROM t2;
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ERROR 42S02: Table 'test.t2' doesn't exist
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SELECT * FROM t1;
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i
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DROP TABLE t1;
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End of 4.1 tests.
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CREATE TABLE t1 ( c FLOAT( 20, 14 ) );
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INSERT INTO t1 VALUES( 12139 );
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CREATE TABLE t2 ( c FLOAT(30,18) );
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INSERT INTO t2 VALUES( 123456 );
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SELECT AVG( c ) FROM t1 UNION SELECT 1;
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AVG( c )
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12139
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1
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SELECT 1 UNION SELECT AVG( c ) FROM t1;
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1
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1
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12139
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SELECT 1 UNION SELECT * FROM t2 UNION SELECT 1;
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1
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1
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123456
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SELECT c/1 FROM t1 UNION SELECT 1;
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c/1
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12139
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1
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DROP TABLE t1, t2;
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