Bug#23656: Wrong conversion result of a DATETIME to integer using CAST function.

The generic string to int conversion was used by the Item_func_signed and
the Item_func_unsigned classes to convert DATE/DATETIME values to the
SIGNED/UNSIGNED type. But this conversion produces wrong results for such
values.

Now if the item which result has to be converted can return its result as
longlong then the item->val_int() method is used to allow the item to carry
out the conversion itself and return the correct result.
This condition is checked in the Item_func_signed::val_int() and the
Item_func_unsigned::val_int() functions.


mysql-test/t/cast.test:
  Added a test case for the bug#23656: Wrong conversion result of a DATETIME to integer using CAST function.
mysql-test/r/cast.result:
  Added a test case for the bug#23656: Wrong conversion result of a DATETIME to integer using CAST function.
sql/item_func.cc:
  Bug#23656: Wrong conversion result of a DATETIME to integer using CAST function.
  Now if the item which result has to be converted can return its result as
  longlong then the item->val_int() method is used to allow the item to carry
  out the conversion itself and return the correct result.
  This condition is checked in the Item_func_signed::val_int() and the
  Item_func_unsigned::val_int() functions.

1 files changed, 6 insertions, 0 deletions

diff --git a/mysql-test/t/cast.test b/mysql-test/t/cast.test
index 7e8ef031e6b..8eef66f9e1b 100644
--- a/mysql-test/t/cast.test
+++ b/mysql-test/t/cast.test
@@ -173,4 +173,10 @@ DROP TABLE t1;
 
 select isnull(date(NULL)), isnull(cast(NULL as DATE));
 
+#
+# Bug#23656: Wrong result of CAST from DATE to int
+#
+SELECT CAST(cast('01-01-01' as date) AS UNSIGNED);
+SELECT CAST(cast('01-01-01' as date) AS SIGNED);
+
 --echo End of 4.1 tests