单项选择题
Given the following two tables:
TAB1 R1
A A A B B C C D E TAB2 R2
A A B B C C D
Which of the following queries returns the following result set? RETVAL E（）
A.SELECT r1 AS retval FROM tab1 INTERSECT SELECT r2 AS retval FROM tab2
B.SELECT r1 AS retval FROM tab1 EXCEPT SELECT r2 AS retval FROM tab2
C.SELECT DISTINCT r1 AS retval FROM tab1, tab2 WHERE r1 <> r2
D.SELECT r1 AS retval FROM tab1 UNION SELECT r2 AS retval FROM tab2
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CREATE TABLE customer (cid BIGINT NOT NULL PRIMARY KEY, info XML) How many names will be returned for this XQuery?（）
A.0
B.1
C.2
D.3 -
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%
