MDEV-10731: Wrong NULL match results in "Subquery returns more than 1 row" (error code 1242)

NOT NULL predicate was not added to tables in case of an update query having a subquery.

mysql-test/r/update_innodb.result

@@ -29,3 +29,29 @@ CREATE ALGORITHM=UNDEFINED VIEW `v1` AS select `t4`.`c1` AS `c1`,`t4`.`c2` AS `c
 UPDATE t1 a JOIN t2 b ON a.c1 = b.c1 JOIN v1 vw ON b.c2 = vw.c1 JOIN t3 del ON vw.c2 = del.c2 SET a.c2 = ( SELECT max(t.c1) FROM t3 t, v1 i WHERE del.c2 = t.c2 AND vw.c3 = i.c3 AND t.c3 = 4 ) WHERE a.c2 IS NULL OR a.c2 < '2011-05-01';
 drop view v1;
 drop table t1,t2,t3,t4;
+#
+# MDEV-10232 Scalar result of subquery changes after adding an outer select stmt
+#
+CREATE TABLE t1 (
+a_id INT(20) UNSIGNED NOT NULL AUTO_INCREMENT,
+b_id INT(20) UNSIGNED NULL DEFAULT NULL,
+c_id VARCHAR(255) NULL DEFAULT NULL,
+PRIMARY KEY (a_id))COLLATE = 'utf8_general_ci' ENGINE = InnoDB;
+CREATE TABLE t2 (
+b_id INT(20) UNSIGNED NOT NULL AUTO_INCREMENT,
+c_id VARCHAR(255) NULL DEFAULT NULL,
+PRIMARY KEY (b_id),
+INDEX idx_c_id (c_id))COLLATE = 'utf8_general_ci' ENGINE = InnoDB;
+INSERT INTO t1 (b_id, c_id) VALUES (NULL, NULL);
+INSERT INTO t2 (c_id) VALUES (NULL);
+INSERT INTO t2 (c_id) VALUES (NULL);
+SELECT * FROM T1;
+a_id	b_id	c_id
+1	NULL	NULL
+SELECT t2.b_id FROM t1,t2 WHERE t2.c_id = t1.c_id;
+b_id
+UPDATE t1 SET b_id = (SELECT t2.b_id FROM t2 t2 WHERE t2.c_id = t1.c_id);
+SELECT * FROM T1;
+a_id	b_id	c_id
+1	NULL	NULL
+drop table t1,t2;

mysql-test/t/update_innodb.test

@@ -37,3 +37,29 @@ UPDATE t1 a JOIN t2 b ON a.c1 = b.c1 JOIN v1 vw ON b.c2 = vw.c1 JOIN t3 del ON v
 
 drop view v1;
 drop table t1,t2,t3,t4;
+
+--echo #
+--echo # MDEV-10232 Scalar result of subquery changes after adding an outer select stmt
+--echo #
+
+CREATE TABLE t1 (
+  a_id INT(20) UNSIGNED NOT NULL AUTO_INCREMENT,
+  b_id INT(20) UNSIGNED NULL DEFAULT NULL,
+  c_id VARCHAR(255) NULL DEFAULT NULL,
+  PRIMARY KEY (a_id))COLLATE = 'utf8_general_ci' ENGINE = InnoDB;
+
+CREATE TABLE t2 (
+  b_id INT(20) UNSIGNED NOT NULL AUTO_INCREMENT,
+  c_id VARCHAR(255) NULL DEFAULT NULL,
+  PRIMARY KEY (b_id),
+  INDEX idx_c_id (c_id))COLLATE = 'utf8_general_ci' ENGINE = InnoDB;
+
+INSERT INTO t1 (b_id, c_id) VALUES (NULL, NULL);
+INSERT INTO t2 (c_id) VALUES (NULL);
+INSERT INTO t2 (c_id) VALUES (NULL);
+
+SELECT * FROM T1;
+SELECT t2.b_id FROM t1,t2 WHERE t2.c_id = t1.c_id;
+UPDATE t1 SET b_id = (SELECT t2.b_id FROM t2 t2 WHERE t2.c_id = t1.c_id);
+SELECT * FROM T1;
+drop table t1,t2;

sql/sql_select.cc

@@ -9367,8 +9367,6 @@ static void add_not_null_conds(JOIN *join)
             UPDATE t1 SET t1.f2=(SELECT MAX(t2.f4) FROM t2 WHERE t2.f3=t1.f1);
             not_null_item is the t1.f1, but it's referred_tab is 0.
           */
-          if (!referred_tab)
-            continue;
           if (!(notnull= new (join->thd->mem_root)
                 Item_func_isnotnull(join->thd, item)))
             DBUG_VOID_RETURN;
@@ -9380,16 +9378,19 @@ static void add_not_null_conds(JOIN *join)
           */
           if (notnull->fix_fields(join->thd, &notnull))
             DBUG_VOID_RETURN;
+
           DBUG_EXECUTE("where",print_where(notnull,
-                                           referred_tab->table->alias.c_ptr(),
+                                            (referred_tab ?
+                                            referred_tab->table->alias.c_ptr() :
+                                            "outer_ref_cond"),
                                             QT_ORDINARY););
           if (!tab->first_inner)
           {
-            COND *new_cond= referred_tab->join == join ? 
+            COND *new_cond= (referred_tab && referred_tab->join == join) ?
                               referred_tab->select_cond :
                               join->outer_ref_cond;
             add_cond_and_fix(join->thd, &new_cond, notnull);
-            if (referred_tab->join == join)
+            if (referred_tab && referred_tab->join == join)
               referred_tab->set_select_cond(new_cond, __LINE__);
             else 
               join->outer_ref_cond= new_cond;