Fix for bug #8143: A date with value 0 is treated as a NULL value

mysql-test/r/delete.result:
  Fix for bug #8143: A date with value 0 is treated as a NULL value
    - test result
mysql-test/t/delete.test:
  Fix for bug #8143: A date with value 0 is treated as a NULL value
    - test case
sql/sql_delete.cc:
  Fix for bug #8143: A date with value 0 is treated as a NULL value
    - during SELECT queries processing we convert 'date[time]_field is null' 
      conditions into 'date[time]_field = 0000-00-00[ 00:00:00]' for not null 
      DATE and DATETIME fields. To be consistent, we have to do the same for DELETE
      queries. So we should call remove_eq_conds() in the mysql_delete() as well.
      Also it may simplify and speed up DELETE queries execution.

1 files changed, 8 insertions, 0 deletions

diff --git a/sql/sql_delete.cc b/sql/sql_delete.cc
index 381d1a71e31..b608773bf6e 100644
--- a/sql/sql_delete.cc
+++ b/sql/sql_delete.cc
@@ -91,6 +91,14 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
     /* Handler didn't support fast delete; Delete rows one by one */
   }
 
+  if (conds)
+  {
+    Item::cond_result result;
+    conds= remove_eq_conds(thd, conds, &result);
+    if (result == Item::COND_FALSE)             // Impossible where
+      limit= 0;
+  }
+
   table->used_keys.clear_all();
   table->quick_keys.clear_all();		// Can't use 'only index'
   select=make_select(table, 0, 0, conds, 0, &error);