Extend QIFEMPTY: empty a) date, b) datetime, c) '0' is also treated as empty.

Documentation/Manual.rst

@@ -6916,7 +6916,7 @@ Output::
 QIFEMPTY: if empty show token
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-The SQL function QIFEMPTY(input, token) returns 'token' if 'input' is empty else 'input'.
+The SQL function QIFEMPTY(input, token) returns 'token' if 'input' is 'empty string' / '0' / '0000-00-00' / '0000-00-00 00:00:00'.
 
 Example::
 

extension/Classes/Sql/function.sql

@@ -71,7 +71,7 @@ END;
 ###
 #
 # QIFEMPTY(input, token)
-# If 'input' is empty, replaces by 'token'
+# If 'input' is empty|0|0000-00-00|0000-00-00 00:00:00, replace by 'token'
 #
 DROP FUNCTION IF EXISTS QIFEMPTY;
 CREATE FUNCTION QIFEMPTY(input TEXT, token TEXT)
@@ -80,7 +80,9 @@ CREATE FUNCTION QIFEMPTY(input TEXT, token TEXT)
   SQL SECURITY INVOKER
 BEGIN
   DECLARE output TEXT;
-  SET output = IF(input = '', token, input);
+  SET output =
+      IF(ISNULL(input) OR input = '' OR INPUT = '0' OR input = '0000-00-00' OR input = '0000-00-00 00:00:00', token,
+         input);
   RETURN output;
 END;