Manual merge

sql/item_cmpfunc.cc:
  Auto merged
mysql-test/r/func_if.result:
  Manual merge.

mysql-test/r/func_if.result

@@ -108,3 +108,16 @@ id	date_ord	text
 2	16-03-2005	Day 2
 1	05-03-2005	Day 1
 DROP TABLE t1;
+CREATE TABLE t1 (a CHAR(10));
+INSERT INTO t1 VALUES ('aaa'), (NULL), (''), ('bbb');
+SELECT a, NULLIF(a,'') FROM t1;
+a	NULLIF(a,'')
+aaa	aaa
+NULL	NULL
+	NULL
+bbb	bbb
+SELECT a, NULLIF(a,'') FROM t1 WHERE NULLIF(a,'') IS NULL;
+a	NULLIF(a,'')
+NULL	NULL
+	NULL
+DROP TABLE t1;

mysql-test/t/func_if.test

@@ -25,10 +25,9 @@ explain extended select if(u=1,st,binary st) s from t1 where st like "%a%" order
 #
 # NULLIF test
 #
-select nullif(u, 1) from t1;
-explain extended select nullif(u, 1) from t1;
+select nullif(u=0, 'test') from t1;
+explain extended select nullif(u=0, 'test') from t1;
 drop table t1;
-select nullif(1,'test');
 
 #
 # Bug 2629
@@ -63,15 +62,13 @@ drop table t1;
 SELECT NULLIF(5,5) IS NULL, NULLIF(5,5) IS NOT NULL;
 
 #
-# Bug #9669 Ordering on IF function with FROM_UNIXTIME function fails
+# Test for bug #11142: evaluation of NULLIF when the first argument is NULL
 #
-CREATE TABLE `t1` (
-  `id` int(11) NOT NULL ,
-  `date` int(10) default NULL,
-  `text` varchar(32) NOT NULL
-);
-INSERT INTO t1 VALUES (1,1110000000,'Day 1'),(2,1111000000,'Day 2'),(3,1112000000,'Day 3');
-SELECT id, IF(date IS NULL, '-', FROM_UNIXTIME(date, '%d-%m-%Y')) AS date_ord, text FROM t1 ORDER BY date_ord ASC;
-SELECT id, IF(date IS NULL, '-', FROM_UNIXTIME(date, '%d-%m-%Y')) AS date_ord, text FROM t1 ORDER BY date_ord DESC;
-DROP TABLE t1;
 
+CREATE TABLE t1 (a CHAR(10));
+INSERT INTO t1 VALUES ('aaa'), (NULL), (''), ('bbb');
+
+SELECT a, NULLIF(a,'') FROM t1;
+SELECT a, NULLIF(a,'') FROM t1 WHERE NULLIF(a,'') IS NULL;
+
+DROP TABLE t1;

sql/item_cmpfunc.cc

@@ -1406,9 +1406,7 @@ Item_func_nullif::val_decimal(my_decimal * decimal_value)
 bool
 Item_func_nullif::is_null()
 {
-  if (!cmp.compare())
-    return (null_value=1);
-  return 0;
+  return (null_value= (!cmp.compare() ? 1 : args[0]->null_value)); 
 }
 
 /*