A fix and a test case for Bug#12734 " prepared statement may

return incorrect result set for a select SQL request"

mysql-test/r/ps.result

@@ -718,3 +718,37 @@ execute stmt;
 drop table t1;
 set names default;
 deallocate prepare stmt;
+create table t1 (
+word_id mediumint(8) unsigned not null default '0',
+formatted varchar(20) not null default ''
+);
+insert into t1 values
+(80,'pendant'), (475,'pretendants'), (989,'tendances'),
+(1019,'cependant'),(1022,'abondance'),(1205,'independants'),
+(13,'lessiver'),(25,'lambiner'),(46,'situer'),(71,'terminer'),
+(82,'decrocher');
+select count(*) from t1 where formatted like '%NDAN%';
+count(*)
+6
+select count(*) from t1 where formatted like '%ER';
+count(*)
+5
+prepare stmt from "select count(*) from t1 where formatted like ?";
+set @like="%NDAN%";
+execute stmt using @like;
+count(*)
+6
+set @like="%ER";
+execute stmt using @like;
+count(*)
+5
+set @like="%NDAN%";
+execute stmt using @like;
+count(*)
+6
+set @like="%ER";
+execute stmt using @like;
+count(*)
+5
+deallocate prepare stmt;
+drop table t1;

mysql-test/t/ps.test

@@ -746,5 +746,35 @@ drop table t1;
 set names default;
 deallocate prepare stmt;
 
+#
+# A test case for Bug#12734 "prepared statement may return incorrect result
+# set for a select SQL request": test that canDoTurboBM is reset for each
+# execute of a prepared statement.
+#
+create table t1 (
+  word_id mediumint(8) unsigned not null default '0',
+  formatted varchar(20) not null default ''
+);
+
+insert into t1 values
+  (80,'pendant'), (475,'pretendants'), (989,'tendances'),
+  (1019,'cependant'),(1022,'abondance'),(1205,'independants'),
+  (13,'lessiver'),(25,'lambiner'),(46,'situer'),(71,'terminer'),
+  (82,'decrocher');
+
+select count(*) from t1 where formatted like '%NDAN%';
+select count(*) from t1 where formatted like '%ER';
+prepare stmt from "select count(*) from t1 where formatted like ?";
+set @like="%NDAN%";
+execute stmt using @like;
+set @like="%ER";
+execute stmt using @like;
+set @like="%NDAN%";
+execute stmt using @like;
+set @like="%ER";
+execute stmt using @like;
+deallocate prepare stmt;
+drop table t1;
+
 # End of 4.1 tests
 

sql/item_cmpfunc.cc

@@ -2524,6 +2524,12 @@ bool Item_func_like::fix_fields(THD *thd, TABLE_LIST *tlist, Item ** ref)
   return 0;
 }
 
+void Item_func_like::cleanup()
+{
+  canDoTurboBM= FALSE;
+  Item_bool_func2::cleanup();
+}
+
 #ifdef USE_REGEX
 
 bool

sql/item_cmpfunc.h

@@ -911,6 +911,7 @@ class Item_func_like :public Item_bool_func2
   cond_result eq_cmp_result() const { return COND_TRUE; }
   const char *func_name() const { return "like"; }
   bool fix_fields(THD *thd, struct st_table_list *tlist, Item **ref);
+  void cleanup();
 };
 
 #ifdef USE_REGEX