单项选择题
A.select * from emp where ename in 'S%'; B.select * from emp where ename='S%'; C.select * from emp where ename like 'S%'; D.select * from emp where ename like 'S_';
A.select to_date(sysdate,'YYYY-MM-DD HH24:MI:SS') from dual; B.select to_char(sysdate,'YYYY-MM-DD HH24:MI:SS') from dual; C.select date(sysdate,'YYYY-MM-DD HH24:MI:SS') from dual; D.select chr(sysdate,'YYYY-MM-DD HH24:MI:SS') from dual;
A.A UNION B B.A UNION ALL B C.A INTERSECT B D.A MIUS B