试题详情
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)

  • B

  • 关注下方微信公众号，在线模考后查看

热门试题