單項選擇題

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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單項選擇題

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

單項選擇題

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)

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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（）

你可能感興趣的試題

CREATE TABLE customer (cid BIGINT NOT NULL PRIMARY KEY, info XML) How many names will be returned for this XQuery?（）

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?（）

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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（）