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/r/cast.result b/mysql-test/r/cast.result
index 23c38bb792c..f6f46bd4079 100644
--- a/mysql-test/r/cast.result
+++ b/mysql-test/r/cast.result
@@ -281,4 +281,10 @@ DROP TABLE t1;
 select isnull(date(NULL)), isnull(cast(NULL as DATE));
 isnull(date(NULL))	isnull(cast(NULL as DATE))
 1	1
+SELECT CAST(cast('01-01-01' as date) AS UNSIGNED);
+CAST(cast('01-01-01' as date) AS UNSIGNED)
+20010101
+SELECT CAST(cast('01-01-01' as date) AS SIGNED);
+CAST(cast('01-01-01' as date) AS SIGNED)
+20010101
 End of 4.1 tests