From e0f0507f999a35362e19ff0d80b3fd2565c83d7c Mon Sep 17 00:00:00 2001
From: "holyfoot/hf@mysql.com/hfmain.(none)" <>
Date: Thu, 22 Mar 2007 12:24:56 +0400
Subject: [PATCH]  bug #16546 (DATETIME + 0 not always coerced in the same way)
   fix for cast( AS DATETIME) + 0 operation.   I just implemented
 Item_datetime_typecast::val() method   as it is usually done in other
 classes.   Should be fixed more radically in 5.0

---
 mysql-test/r/type_datetime.result | 3 +++
 mysql-test/t/type_datetime.test   | 6 ++++++
 sql/item_timefunc.h               | 7 +++++++
 3 files changed, 16 insertions(+)

diff --git a/mysql-test/r/type_datetime.result b/mysql-test/r/type_datetime.result
index f313a6b934b..64337bd2c2f 100644
--- a/mysql-test/r/type_datetime.result
+++ b/mysql-test/r/type_datetime.result
@@ -166,3 +166,6 @@ dt
 0000-00-00 00:00:00
 0000-00-00 00:00:00
 drop table t1;
+select cast('2006-12-05 22:10:10' as datetime) + 0;
+cast('2006-12-05 22:10:10' as datetime) + 0
+20061205221010.000000
diff --git a/mysql-test/t/type_datetime.test b/mysql-test/t/type_datetime.test
index 4b6741b4242..87b86b55fc9 100644
--- a/mysql-test/t/type_datetime.test
+++ b/mysql-test/t/type_datetime.test
@@ -113,4 +113,10 @@ insert into t1 values ("00-00-00"), ("00-00-00 00:00:00");
 select * from t1;
 drop table t1;
 
+#
+# Bug #16546 DATETIME+0 not always coerced the same way 
+#
+select cast('2006-12-05 22:10:10' as datetime) + 0;
+
+
 # End of 4.1 tests
diff --git a/sql/item_timefunc.h b/sql/item_timefunc.h
index 45cad627c05..2383b4f86ac 100644
--- a/sql/item_timefunc.h
+++ b/sql/item_timefunc.h
@@ -751,12 +751,19 @@ public:
   String *val_str(String *str);
   const char *cast_type() const { return "datetime"; }
   enum_field_types field_type() const { return MYSQL_TYPE_DATETIME; }
+  void fix_length_and_dec()
+  {
+    Item_typecast_maybe_null::fix_length_and_dec();
+    decimals= DATETIME_DEC;
+  }
+
   Field *tmp_table_field(TABLE *t_arg)
   {
     return (new Field_datetime(maybe_null, name, t_arg, &my_charset_bin));
   }
   bool result_as_longlong() { return TRUE; }
   longlong val_int();
+  double val() { return (double) val_int(); }
 };
 
 class Item_func_makedate :public Item_str_func