比如查询select * from merger_1 where gridID in (123,3453,34643 ) union all select * from merger_2 where gridID in (123,3453,34643 ) union all select * from merger_3 where gridID in (123,3453,34643 ) union all select * from merger_4 where gridID in (123,3453,34643 ) union all select * from merger_5 where gridID in (123,3453,34643 )
我想知道这个查询的 结果集有多少!
我想知道这个查询的 结果集有多少!
select * from merger_1 where gridID in (123,3453,34643 )
union all
select * from merger_2 where gridID in (123,3453,34643 )
union all
select * from merger_3 where gridID in (123,3453,34643 )
union all
select * from merger_4 where gridID in (123,3453,34643 )
union all
select * from merger_5 where gridID in (123,3453,34643 )
) t
select * from merger_1 where gridID in (123,3453,34643 )
union all
select * from merger_2 where gridID in (123,3453,34643 )
union all
select * from merger_3 where gridID in (123,3453,34643 )
union all
select * from merger_4 where gridID in (123,3453,34643 )
union all
select * from merger_5 where gridID in (123,3453,34643 )后直接 SELECT FOUND_ROWS();
select count(*) from (
select * from merger_1 where gridID in (123,3453,34643 ) union all select * from merger_2 where gridID in (123,3453,34643 ) union all select * from merger_3 where gridID in (123,3453,34643 ) union all select * from merger_4 where gridID in (123,3453,34643 ) union all select * from merger_5 where gridID in (123,3453,34643 ) ) a