create table t1 (id1 int);

create table t2 (id2 int);

select id1 from t1 for update

union

select id2 from t2 for update;

drop table t1,t2;

create table t1 (id1 int);

create table t2 (id2 int);

select id1 from t1 limit 1

union

select id2 from t2 limit 1;

drop table t1,t2;

/*

  query_expression_body produces the same expressions as

      <query expression body>

*/

query_expression_body:

          query_simple 

          {

            Lex->push_select($1);

            if (!($$= Lex->create_unit($1)))

              MYSQL_YYABORT;

          }

        | query_expression_body

          unit_type_decl

          {

            if (!$1->first_select()->next_select())

            {

              Lex->pop_select();

            }

          }

          query_primary

          {

            if (!($$= Lex->add_primary_to_query_expression_body($1, $4,

                                                                $2.unit_type,

                                                                $2.distinct,

                                                                FALSE)))

              MYSQL_YYABORT;

          }

        | query_expression_body_ext_parens

          unit_type_decl

          query_primary

          {

            if (!($$= Lex->add_primary_to_query_expression_body_ext_parens(

                                                                $1, $3,

                                                                $2.unit_type,

                                                                $2.distinct)))

              MYSQL_YYABORT;

          }

        ;

    <query expression> ::=

     [ <with clause> ] <query expression body>

       [ <order by clause> ] [ <result offset clause> ] [ <fetch first clause> ]

   <with clause> ::=

     WITH [ RECURSIVE ] <with_list

   <with list> ::=

     <with list element> [ { <comma> <with list element> }... ]

   <with list element> ::=

     <query name> [ '(' <with column list> ')' ]

         AS <table subquery>

   <with column list> ::=

     <column name list>

   <query expression body> ::

       <query term>

     | <query expression body> UNION [ ALL | DISTINCT ] <query term>

     | <query expression body> EXCEPT [ DISTINCT ] <query term>

   <query term> ::=

       <query primary>

     | <query term> INTERSECT [ DISTINCT ] <query primary>

   <query primary> ::=

       <simple table>

     | '(' <query expression body>

       [ <order by clause> ] [ <result offset clause> ] [ <fetch first clause> ]

       ')'

   <simple table>

       <query specification>

     | <table value constructor>

  <subquery>

       '(' <query_expression> ')'

  <query specification> ::=

         SELECT [ <set quantifier> ] <select list> <table expression>