A.SELECT * FROM student where id=l,2,3:
B.SELECT * FROM student where (id=1, id=2, id=3)
C.SELECT * FROM student where id in (1,2,3)
D.SELECT * FROM student where id in 1,2,3
在SQL SELECT语句中用于实现关系的选择运算的短语是( )
A) FOR B) WHERE
C) WHILE D) CONDITION
A.SELECT empno,ename FROM empWHERE empno=(SELECT empno FROM dept WHERE dname="研发部")
B.SELECT empno,ename FROM empWHERE deptno=(SELECT deptno FROM dept WHERE dname='研发部')
C.SELECT empno,ename FROM empWHERE deptno=(SELECT * FROM dept WHERE dname='研发部')
D.SELECT empno,ename FROM deptWHERE deptno=(SELECT deptno FROM emp WHERE dname="研发部")
A.定义规图的用户必须对所参照的表或视图有查询权限
B.不能包含FROM子句中的子查询
C.不能引用系统或用户变量
D.在视图定义中不允许使用ORDERBY