From 697836c77fb9af725a5d9698bd6a169096b2b36c Mon Sep 17 00:00:00 2001
From: "evgen@moonbone.local" <>
Date: Thu, 4 Aug 2005 18:05:33 +0400
Subject: [PATCH] Fix bug#12266 GROUP BY DATE(LEFT(column,8)) returns result
 strings with reduced length.

When temporary field created for DATE(LEFT(column,8)) expression, max_length
value is taken from Item_date_typecast, and it is getting it from underlaid
Item_func_left and it's max_length is 8 in given expression. And all this
results in stripping last 2 digits.

To Item_date_typecast class added its own fix_length_and_dec() function
that sets max_length value to 10, which is proper for DATE field.
---
 mysql-test/r/group_by.result |  7 +++++++
 mysql-test/t/group_by.test   | 10 ++++++++++
 sql/item_timefunc.h          |  6 ++++++
 3 files changed, 23 insertions(+)

diff --git a/mysql-test/r/group_by.result b/mysql-test/r/group_by.result
index 295663fe1d3..8287a042d60 100644
--- a/mysql-test/r/group_by.result
+++ b/mysql-test/r/group_by.result
@@ -757,3 +757,10 @@ SELECT n+1 AS n FROM t1 GROUP BY n;
 n
 2
 DROP TABLE t1;
+create table t1 (f1 date);
+insert into t1 values('2005-06-06');
+insert into t1 values('2005-06-06');
+select date(left(f1+0,8)) from t1 group by 1;
+date(left(f1+0,8))
+2005-06-06
+drop table t1;
diff --git a/mysql-test/t/group_by.test b/mysql-test/t/group_by.test
index c07d309005e..815da66c717 100644
--- a/mysql-test/t/group_by.test
+++ b/mysql-test/t/group_by.test
@@ -590,4 +590,14 @@ INSERT INTO t1 VALUES (1);
 SELECT n+1 AS n FROM t1 GROUP BY n;
 DROP TABLE t1;
 
+#
+# Bug #12266 GROUP BY expression on DATE column produces result with
+#            reduced length
+#
+create table t1 (f1 date);
+insert into t1 values('2005-06-06');
+insert into t1 values('2005-06-06'); 
+select date(left(f1+0,8)) from t1 group by 1;
+drop table t1;
+
 # End of 4.1 tests
diff --git a/sql/item_timefunc.h b/sql/item_timefunc.h
index 1a30b24b7ce..0df84d14bea 100644
--- a/sql/item_timefunc.h
+++ b/sql/item_timefunc.h
@@ -709,6 +709,12 @@ public:
   {
     return (new Field_date(maybe_null, name, t_arg, &my_charset_bin));
   }  
+  void fix_length_and_dec()
+  {
+    collation.set(&my_charset_bin);
+    max_length= 10;
+    maybe_null= 1;
+  }
 };