拼接2个以上select语句查询结果集,用以下( )个语句。
A. order by
B. union
C. join
D. from
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排序用下面( )个子句。
A. group by
B. order by
C. ASC
D. where
求平均值用( )个聚合函数。
A. avg( )
B. max( )
C. average( )
D. mean( )
分组查询的关键字是( )
A. order by
B. from
C. group by
D. group
where子句、group by子句、having子句在select语句中的顺序是()
A. having子句、group by子句、where子句
B. group by子句、having子句、where子句
C. group by子句、where子句、having子句
D. where子句、group by子句、having子句
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