MDEV-7759 NULLIF(x,y) is not equal to CASE WHEN x=y THEN NULL ELSE x END

1 files changed, 9 insertions, 0 deletions

diff --git a/sql/item_func.h b/sql/item_func.h
index 3c46d6549a0..84454ad2290 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -398,6 +398,15 @@ public:
     walk(&Item::call_bool_func_processor, FALSE, (uchar*) &info);
   }
   void convert_const_compared_to_int_field(THD *thd);
+  /**
+    Prepare arguments and setup a comparator.
+    Used in Item_func_xxx with two arguments and a comparator,
+    e.g. Item_bool_func2 and Item_func_nullif.
+    args[0] or args[1] can be modified:
+    - converted to character set and collation of the operation
+    - or replaced to an Item_int_with_ref
+  */
+  bool setup_args_and_comparator(THD *thd, Arg_comparator *cmp);
 };