MDEV-13695: INTERSECT precedence is not in line with Oracle even in SQL_MODE=Oracle

Switch off automatic INTERSECT  priority for ORACLE MODE

mysql-test/main/intersect.result

@@ -607,6 +607,22 @@ NULL	INTERSECT RESULT	<intersect2,4>	ALL	NULL	NULL	NULL	NULL	NULL	NULL
 NULL	UNION RESULT	<union1,3,5>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	
 Warnings:
 Note	1003	(/* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1`) union /* select#3 */ select `__3`.`c` AS `c`,`__3`.`d` AS `d` from ((/* select#2 */ select `test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2`) intersect (/* select#4 */ select `test`.`t3`.`e` AS `e`,`test`.`t3`.`f` AS `f` from `test`.`t3`)) `__3` union (/* select#5 */ select 4 AS `4`,4 AS `4`)
+set SQL_MODE=ORACLE;
+(select a,b from t1) union (select c,d from t2) intersect (select e,f from t3) union (select 4,4);
+a	b
+3	3
+4	4
+explain extended
+(select a,b from t1) union (select c,d from t2) intersect (select e,f from t3) union (select 4,4);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
+2	UNION	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	
+3	INTERSECT	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	
+4	UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+NULL	UNIT RESULT	<unit1,2,3,4>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	
+Warnings:
+Note	1003	(/* select#1 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from "test"."t1") union (/* select#2 */ select "test"."t2"."c" AS "c","test"."t2"."d" AS "d" from "test"."t2") intersect (/* select#3 */ select "test"."t3"."e" AS "e","test"."t3"."f" AS "f" from "test"."t3") union (/* select#4 */ select 4 AS "4",4 AS "4")
+set SQL_MODE=default;
 (select e,f from t3) intersect (select c,d from t2) union (select a,b from t1) union (select 4,4);
 e	f
 3	3
@@ -623,6 +639,24 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 NULL	UNIT RESULT	<unit1,2,3,4>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	
 Warnings:
 Note	1003	(/* select#1 */ select `test`.`t3`.`e` AS `e`,`test`.`t3`.`f` AS `f` from `test`.`t3`) intersect (/* select#2 */ select `test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2`) union (/* select#3 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1`) union (/* select#4 */ select 4 AS `4`,4 AS `4`)
+set SQL_MODE=ORACLE;
+(select e,f from t3) intersect (select c,d from t2) union (select a,b from t1) union (select 4,4);
+e	f
+3	3
+4	4
+5	5
+6	6
+explain extended
+(select e,f from t3) intersect (select c,d from t2) union (select a,b from t1) union (select 4,4);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	100.00	
+2	INTERSECT	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	
+3	UNION	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
+4	UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+NULL	UNIT RESULT	<unit1,2,3,4>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	
+Warnings:
+Note	1003	(/* select#1 */ select "test"."t3"."e" AS "e","test"."t3"."f" AS "f" from "test"."t3") intersect (/* select#2 */ select "test"."t2"."c" AS "c","test"."t2"."d" AS "d" from "test"."t2") union (/* select#3 */ select "test"."t1"."a" AS "a","test"."t1"."b" AS "b" from "test"."t1") union (/* select#4 */ select 4 AS "4",4 AS "4")
+set SQL_MODE=default;
 (/* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1`) union /* select#3 */ select `__3`.`c` AS `c`,`__3`.`d` AS `d` from ((/* select#2 */ select `test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2`) intersect (/* select#4 */ select `test`.`t3`.`e` AS `e`,`test`.`t3`.`f` AS `f` from `test`.`t3`)) `__3` union (/* select#5 */ select 4 AS `4`,4 AS `4`);
 a	b
 3	3
@@ -772,4 +806,30 @@ SELECT * FROM t1 LEFT OUTER JOIN t2 LEFT OUTER JOIN t3 ON b < c ON a > b
 count(*)
 14848
 drop table t1,t2,t3;
+#
+# MDEV-13695: INTERSECT precedence is not in line with Oracle even
+# in SQL_MODE=Oracle
+#
+create table t12(c1 int);
+insert into t12 values(1);
+insert into t12 values(2);
+create table t13(c1 int);
+insert into t13 values(1);
+insert into t13 values(3);
+create table t234(c1 int);
+insert into t234 values(2);
+insert into t234 values(3);
+insert into t234 values(4);
+set SQL_MODE=oracle;
+select * from t13 union select * from t234 intersect select * from t12;
+c1
+1
+2
+set SQL_MODE=default;
+select * from t13 union select * from t234 intersect select * from t12;
+c1
+1
+2
+3
+drop table t12,t13,t234;
 # End of 10.3 tests

mysql-test/main/intersect.test

@@ -147,12 +147,25 @@ insert into t3 values (1,1),(3,3);
 (select a,b from t1) union (select c,d from t2) intersect (select e,f from t3) union (select 4,4);
 explain extended
 (select a,b from t1) union (select c,d from t2) intersect (select e,f from t3) union (select 4,4);
+set SQL_MODE=ORACLE;
+--sorted_result
+(select a,b from t1) union (select c,d from t2) intersect (select e,f from t3) union (select 4,4);
+explain extended
+(select a,b from t1) union (select c,d from t2) intersect (select e,f from t3) union (select 4,4);
+set SQL_MODE=default;
+
 
 # test result of linear mix operation 
 --sorted_result
 (select e,f from t3) intersect (select c,d from t2) union (select a,b from t1) union (select 4,4);
 explain extended
 (select e,f from t3) intersect (select c,d from t2) union (select a,b from t1) union (select 4,4);
+set SQL_MODE=ORACLE;
+--sorted_result
+(select e,f from t3) intersect (select c,d from t2) union (select a,b from t1) union (select 4,4);
+explain extended
+(select e,f from t3) intersect (select c,d from t2) union (select a,b from t1) union (select 4,4);
+set SQL_MODE=default;
 
 --sorted_result
 (/* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1`) union /* select#3 */ select `__3`.`c` AS `c`,`__3`.`d` AS `d` from ((/* select#2 */ select `test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2`) intersect (/* select#4 */ select `test`.`t3`.`e` AS `e`,`test`.`t3`.`f` AS `f` from `test`.`t3`)) `__3` union (/* select#5 */ select 4 AS `4`,4 AS `4`);
@@ -282,4 +295,29 @@ select count(*) from (
 
 drop table t1,t2,t3;
 
+--echo #
+--echo # MDEV-13695: INTERSECT precedence is not in line with Oracle even
+--echo # in SQL_MODE=Oracle
+--echo #
+
+create table t12(c1 int);
+insert into t12 values(1);
+insert into t12 values(2);
+create table t13(c1 int);
+insert into t13 values(1);
+insert into t13 values(3);
+create table t234(c1 int);
+insert into t234 values(2);
+insert into t234 values(3);
+insert into t234 values(4);
+ 
+set SQL_MODE=oracle;
+--sorted_result
+select * from t13 union select * from t234 intersect select * from t12;
+set SQL_MODE=default;
+--sorted_result
+select * from t13 union select * from t234 intersect select * from t12;
+
+drop table t12,t13,t234;
+
 --echo # End of 10.3 tests

sql/sql_yacc.yy

@@ -546,7 +546,8 @@ bool LEX::add_select_to_union_list(bool is_union_distinct,
     as possible */
   if (type == INTERSECT_TYPE &&
       (current_select->linkage != INTERSECT_TYPE &&
-       current_select != current_select->master_unit()->first_select()))
+       current_select != current_select->master_unit()->first_select())
+     && !(thd->variables.sql_mode & MODE_ORACLE))
   {
     /*
       This and previous SELECTs should go one level down because of