CREATE TABLE customer (cid BIGINT NOT NULL PRIMARY KEY,……

单项选择题Which of the following SQL statements will return the year and average salary for all employees hired within a given year that have a salary greater than $30,000?（）

A.SELECT * FROM t1 UNION SELECT * FROM t2
B.SELECT * FROM t1 UNION DISTINCT SELECT * FROM t2
C.SELECT * FROM t1 INTERSECT SELECT * FROM t2
D.SELECT * FROM t1 WHERE (c1,c2)= (SELECT c1,c2 FROM t2)

单项选择题Given the following table definition: STOCK: item VARCHAR(30) status CHAR(1) quantity INT price DEC(7,2) If items are indicated to be out of stock by setting STATUS to NULL and QUANTITY and PRICE to zero, which of the following statements would be used to update the STOCK table to indicate that all the items whose description begins with the letter S are out of stock?（）

A.UPDATE stock SET (status = NULL; quantity, price = 0) WHERE item LIKE S%
B.UPDATE stock SET (status, quantity, price) = (NULL, 0, 0) WHERE item LIKE S%
C.UPDATE stock SET status = NULL, SET quantity = 0, SET price = 0 WHERE item LIKE 'S%'
D.UPDATE stock SET (status = NULL), (quantity = 0), (price = 0) WHERE item LIKE S%

单项选择题The EMPLOYEE table contains the following information: EMPNO NAME WORKDEPT 101 SAM A11 102 JOHN C12 103 JANE -104 PAT Remote 105 ANNE -106 BOB A11 The MANAGER table contains the following information: MGRID NAME DEPTNO EMPCOUNT 1 WU B01 - 2 JONES A11 - 3 CHEN - - 4 SMITH - -5 THOMAS C12 - After this statement is executed: UPDATE manager m SET empcount = (SELECT COUNT(workdept) FROM employee e WHERE workdept=m.deptno) What is the result of the following query?（） SELECT mgrid, empcount FROM MANAGER WHERE empcount IS NOT NULL ORDER BY mgrid

A. MGRID EMPCOUNT ----- -------- 1 0 2 2 5 1
B. MGRID EMPCOUNT ----- -------- 1 0 2 2 3 0 4 0 5 1
C. MGRID EMPCOUNT ----- -------- 1 3 2 3 3 3 4 3 5 3
D. MGRID EMPCOUNT ----- -------- 1 0 2 2 3 2 4 2 5 1

单项选择题Which of the following will begin a new unit of work?（）

A.The CONNECT statement
B.The first FETCH of a cursor
C.The BEGIN TRANSACTION statement
D.The first executable SQL statement

单项选择题Given that tables T1 and T2 contain the following rows: Table T1: C1 C2 1 4 1 3 1 2 Table T2: C1 C2 1 1 1 2 1 3 Which of the following queries will return only those rows that exist in both T1 and T2?（）

A.SELECT * FROM t1 UNION SELECT * FROM t2
B.SELECT * FROM t1 UNION DISTINCT SELECT * FROM t2
C.SELECT * FROM t1 INTERSECT SELECT * FROM t2
D.SELECT * FROM t1 WHERE (c1,c2)= (SELECT c1,c2 FROM t2)