Which SQL statement is the trump card to the senior software developer

WithinsomanykindsofDMLstatementsinSQL,Ithinkfourkindsofthem,includingCaseWhen,LeftOuterJoin/LeftJoin/RightOuterJoin/RightJoin/InnerJoin,WITHASandUNION/UNIONALL,areessentialfortheDatabaseDeveloper.Infact,thereisakindofSQLstatementwhichmightbethetrumpcardtotheseniorsoftwarede