查询tb_ book表中useno字段的记录,并去除重复值的是()。
A. SELECT DISTINCT userno FROM tb_ book;
B. SELECT userno DITINCT FROM tb_book;
C. SELECT DITINCT(userno) FROM tb_book;
D. SELECT userno FROM DISTINCT tb_book;
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查询tb001数据表中的前5条记录,并升序排列,语法格式是( )。
A. SELECT * FROM tb001 WHERE ORDER BY id ASC LIMIT 0,5;
B. SELECT * FROM tb001 WHERE ORDER BY id DESC LIMIT 0,5;
C. SELECT * FROM tb001 WHERE ORDER BY id GROUP BY LIMIT 0,5;
D. SELECT * FROM tb001 WHERE ORDER BY id ORDER LIMIT 0,5;
SQL语言中,删除EMP表中全部数据的命令正确的是( )。
A. DELETE * FROM emp
B. DROP TABLE emp
C. TRUNCATE TABLE emp
D. 没有正确答案
下面正确表示Employees表中有多少非NULL的Region列的SQL语句是()。
A. SELECT COUNT( * ) FROM Employees
B. SELECT COUNT( ALL Region) FROM Fmnl.
C. SLECT COUNT(DISTINCT Regio) FROM Emploree
D. SELECT SUM( ALL Region) FROM Emplyees
下面可以通过聚合两数的结果来过速查询结果集的SOL子句是( )。
A. WHERE 子旬
B. GROUP BY子句
C. HAVING子句
D. ORDER BY子句