单项选择题
A.SELECT * FROM tab1 INNER JOIN tab2 ON c1=cx
B.SELECT * FROM tab1 LEFT OUTER JOIN tab2 ON c1=cx
C.SELECT * FROM tab1 FULL OUTER JOIN tab2 ON c1=cx
D.SELECT * FROM tab1 RIGHT OUTER JOIN tab2 ON c1=cx
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（）
单项选择题 CREATE TABLE customer (cid BIGINT NOT NULL PRIMARY KEY, info XML) How many names will be returned for this XQuery?（）
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?（）