SET sql_mode=ORACLE;
#
# MDEV-29095 REGEXP_REPLACE treats empty strings different than REPLACE in ORACLE mode
#
CREATE TABLE t1 (replacement VARCHAR(10));
INSERT INTO t1 VALUES (NULL), ('');
SELECT replacement, REGEXP_REPLACE('abba','a',replacement) FROM t1 ORDER BY replacement;
replacement	REGEXP_REPLACE('abba','a',replacement)
NULL	bb
	bb
DROP TABLE t1;
SELECT REGEXP_REPLACE('abba','a',null);
REGEXP_REPLACE('abba','a',null)
bb
EXPLAIN EXTENDED SELECT REPLACE('abba','a',null) ;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
Warnings:
Note	1003	select replace('abba','a',NULL) AS "REPLACE('abba','a',null)"
CREATE VIEW v1 AS SELECT REPLACE('abba','a',null) ;
SHOW CREATE VIEW v1;
View	Create View	character_set_client	collation_connection
v1	CREATE VIEW "v1" AS select replace('abba','a',NULL) AS "REPLACE('abba','a',null)"	latin1	latin1_swedish_ci
SELECT * FROM v1;
REPLACE('abba','a',null)
bb
SET sql_mode=DEFAULT;
SHOW CREATE VIEW v1;
View	Create View	character_set_client	collation_connection
v1	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v1` AS select oracle_schema.replace('abba','a',NULL) AS `REPLACE('abba','a',null)`	latin1	latin1_swedish_ci
SELECT * FROM v1;
REPLACE('abba','a',null)
bb
DROP VIEW v1;