MDEV-5702 Incorrect results are returned with NULLIF()

mysql-test/include/ctype_numconv.inc

@@ -1794,6 +1794,17 @@ SELECT f1() FROM t1 LEFT JOIN (SELECT 1 AS a FROM t1 LIMIT 0) AS d ON 1 GROUP BY
 DROP FUNCTION f1;
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-5702 Incorrect results are returned with NULLIF()
+--echo #
+CREATE TABLE t1 (d DATE);
+INSERT INTO t1 VALUES ('1999-11-11'),('2014-02-04');
+SELECT DISTINCT d, CAST(d AS CHAR), NULLIF(d,"2000-01-01") AS bad, NULLIF(CAST(d AS CHAR),"2000-01-01") AS good FROM t1;
+CREATE TABLE t2 AS SELECT DISTINCT d, NULLIF(d,'2000-01-01') AS bad FROM t1;
+SHOW CREATE TABLE t2;
+DROP TABLE t1, t2;
+
+
 SET NAMES latin1;
 SET sql_mode='';
 CREATE TABLE t1(a char(215) CHARACTER SET utf8 NOT NULL DEFAULT '', KEY(a));

mysql-test/r/ctype_binary.result

@@ -2848,6 +2848,23 @@ f1()
 00:00:01
 DROP FUNCTION f1;
 DROP TABLE t1;
+#
+# MDEV-5702 Incorrect results are returned with NULLIF()
+#
+CREATE TABLE t1 (d DATE);
+INSERT INTO t1 VALUES ('1999-11-11'),('2014-02-04');
+SELECT DISTINCT d, CAST(d AS CHAR), NULLIF(d,"2000-01-01") AS bad, NULLIF(CAST(d AS CHAR),"2000-01-01") AS good FROM t1;
+d	CAST(d AS CHAR)	bad	good
+1999-11-11	1999-11-11	1999-11-11	1999-11-11
+2014-02-04	2014-02-04	2014-02-04	2014-02-04
+CREATE TABLE t2 AS SELECT DISTINCT d, NULLIF(d,'2000-01-01') AS bad FROM t1;
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `d` date DEFAULT NULL,
+  `bad` varbinary(10) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1, t2;
 SET NAMES latin1;
 SET sql_mode='';
 CREATE TABLE t1(a char(215) CHARACTER SET utf8 NOT NULL DEFAULT '', KEY(a));

mysql-test/r/ctype_cp1251.result

@@ -3240,6 +3240,23 @@ f1()
 00:00:01
 DROP FUNCTION f1;
 DROP TABLE t1;
+#
+# MDEV-5702 Incorrect results are returned with NULLIF()
+#
+CREATE TABLE t1 (d DATE);
+INSERT INTO t1 VALUES ('1999-11-11'),('2014-02-04');
+SELECT DISTINCT d, CAST(d AS CHAR), NULLIF(d,"2000-01-01") AS bad, NULLIF(CAST(d AS CHAR),"2000-01-01") AS good FROM t1;
+d	CAST(d AS CHAR)	bad	good
+1999-11-11	1999-11-11	1999-11-11	1999-11-11
+2014-02-04	2014-02-04	2014-02-04	2014-02-04
+CREATE TABLE t2 AS SELECT DISTINCT d, NULLIF(d,'2000-01-01') AS bad FROM t1;
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `d` date DEFAULT NULL,
+  `bad` varchar(10) CHARACTER SET cp1251 DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1, t2;
 SET NAMES latin1;
 SET sql_mode='';
 CREATE TABLE t1(a char(215) CHARACTER SET utf8 NOT NULL DEFAULT '', KEY(a));

mysql-test/r/ctype_latin1.result

@@ -3422,6 +3422,23 @@ f1()
 00:00:01
 DROP FUNCTION f1;
 DROP TABLE t1;
+#
+# MDEV-5702 Incorrect results are returned with NULLIF()
+#
+CREATE TABLE t1 (d DATE);
+INSERT INTO t1 VALUES ('1999-11-11'),('2014-02-04');
+SELECT DISTINCT d, CAST(d AS CHAR), NULLIF(d,"2000-01-01") AS bad, NULLIF(CAST(d AS CHAR),"2000-01-01") AS good FROM t1;
+d	CAST(d AS CHAR)	bad	good
+1999-11-11	1999-11-11	1999-11-11	1999-11-11
+2014-02-04	2014-02-04	2014-02-04	2014-02-04
+CREATE TABLE t2 AS SELECT DISTINCT d, NULLIF(d,'2000-01-01') AS bad FROM t1;
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `d` date DEFAULT NULL,
+  `bad` varchar(10) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1, t2;
 SET NAMES latin1;
 SET sql_mode='';
 CREATE TABLE t1(a char(215) CHARACTER SET utf8 NOT NULL DEFAULT '', KEY(a));

mysql-test/r/ctype_ucs.result

@@ -4238,6 +4238,23 @@ f1()
 00:00:01
 DROP FUNCTION f1;
 DROP TABLE t1;
+#
+# MDEV-5702 Incorrect results are returned with NULLIF()
+#
+CREATE TABLE t1 (d DATE);
+INSERT INTO t1 VALUES ('1999-11-11'),('2014-02-04');
+SELECT DISTINCT d, CAST(d AS CHAR), NULLIF(d,"2000-01-01") AS bad, NULLIF(CAST(d AS CHAR),"2000-01-01") AS good FROM t1;
+d	CAST(d AS CHAR)	bad	good
+1999-11-11	1999-11-11	1999-11-11	1999-11-11
+2014-02-04	2014-02-04	2014-02-04	2014-02-04
+CREATE TABLE t2 AS SELECT DISTINCT d, NULLIF(d,'2000-01-01') AS bad FROM t1;
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `d` date DEFAULT NULL,
+  `bad` varchar(10) CHARACTER SET ucs2 DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1, t2;
 SET NAMES latin1;
 SET sql_mode='';
 CREATE TABLE t1(a char(215) CHARACTER SET utf8 NOT NULL DEFAULT '', KEY(a));

mysql-test/r/ctype_utf8.result

@@ -5059,6 +5059,23 @@ f1()
 00:00:01
 DROP FUNCTION f1;
 DROP TABLE t1;
+#
+# MDEV-5702 Incorrect results are returned with NULLIF()
+#
+CREATE TABLE t1 (d DATE);
+INSERT INTO t1 VALUES ('1999-11-11'),('2014-02-04');
+SELECT DISTINCT d, CAST(d AS CHAR), NULLIF(d,"2000-01-01") AS bad, NULLIF(CAST(d AS CHAR),"2000-01-01") AS good FROM t1;
+d	CAST(d AS CHAR)	bad	good
+1999-11-11	1999-11-11	1999-11-11	1999-11-11
+2014-02-04	2014-02-04	2014-02-04	2014-02-04
+CREATE TABLE t2 AS SELECT DISTINCT d, NULLIF(d,'2000-01-01') AS bad FROM t1;
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `d` date DEFAULT NULL,
+  `bad` varchar(10) CHARACTER SET utf8 DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1, t2;
 SET NAMES latin1;
 SET sql_mode='';
 CREATE TABLE t1(a char(215) CHARACTER SET utf8 NOT NULL DEFAULT '', KEY(a));

sql/item_cmpfunc.cc

@@ -2723,13 +2723,13 @@ Item_func_nullif::fix_length_and_dec()
   maybe_null=1;
   if (args[0])					// Only false if EOM
   {
-    max_length=args[0]->max_length;
     decimals=args[0]->decimals;
     unsigned_flag= args[0]->unsigned_flag;
     cached_result_type= args[0]->result_type();
     if (cached_result_type == STRING_RESULT &&
         agg_arg_charsets_for_comparison(collation, args, arg_count))
       return;
+    fix_char_length(args[0]->max_char_length());
   }
 }