如题,不知道这种查询是怎样的用法,还请各位指教!

select A.col_1,B.col_1 from Table_1 A left join Table_2 B on A.col_2=B.col_2

select A.col_1,B.col_1 from Table_1 A right join Table_2 B on A.col_2=B.col_2