select * from a union select * from b 能详细说下么

select * from a union select * from b 能详细说下么 select * into b from a where 11 select count(c) from (select b from TUserBankLogSum b group insert into a select * from b 和select * into a from b 这两个语句是 select ** from A where A.id in (select id from B where ****) SQL语句理解 select * from B where (select count(1) as num from A ms sql :select * from (select *from b) as xxx where 和 select 解释数SQL面的 select * from a, b 是什么意思 select * from a,b与select * from a inner join b 的取数方式和执行效率有什么 select*from ‘ * ’ 的意义? select * from book limit , select A,B,C,D=(select count(*) from 表 where c=a.a and b=a.b