（141）View the Exhibit and examine the structure of CUSTOMERS and GRADES tables.

You need to display names and grades of customers who have the highest credit limit.

Which two SQL statements would accomplish the task?

A.

SELECT custname, grade FROM customers, grades

WHERE (SELECT MAX(cust_credit_limit) FROM customers) BETWEEN startval and endval;

B.

SELECT custname, grade FROM customers, grades

WHERE (SELECT MAX(cust_credit_limit) FROM customers) BETWEEN startval and endval

AND cust_credit_limit BETWEEN startval AND endval;

C.

SELECT custname, grade FROM customers, grades

WHERE cust_credit_limit = (SELECT MAX(cust_credit_limit) FROM customers)

AND cust_credit_limit BETWEEN startval AND endval;

D.

SELECT custname, grade FROM customers , grades

WHERE cust_credit_limit IN (SELECT MAX(cust_credit_limit) FROM customers)

AND MAX(cust_credit_limit) BETWEEN startval AND endval;

答案：（C）

解析：

D（X），最后一句AND MAX(cust_credit_limit) BETWEEN，多了一个MAX

-- A(X)

scott@TESTDB11>select e.empno, e.ename, e.sal, s.grade

2 from emp e, salgrade s

3 where (select max(sal) from emp) between s.losal and s.hisal;

-- B(X)

scott@TESTDB11>select e.empno, e.ename, e.sal, s.grade

2 from emp e, salgrade s

3 where (select max(sal) from emp) between losal and hisal

4 and sal between losal and hisal;

--C

scott@TESTDB11>select e.empno, e.ename, e.sal, s.grade

2 from emp e, salgrade s

3 where sal = (select max(sal) from emp)

4 and sal between s.losal and s.hisal;

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