题目内容

使用关键字（）可以查询表中前N条数据。

A. DISTINCT
B. UNION
C. ALL
D. TOP

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如果要在WHERE子句中判断某元组的某一字段（假设是FieldName）是否为空值，可以使用 FieldName IS NULL 语法，也可以使用 FieldName = NULL 语法。

A. 对
B. 错

假设某同学年龄为30岁(Sage=30)，另一个同学年龄为20岁(Sage=20)，则他们都不满足 Sage BETWEEN 20 AND 30.

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可以为SELECT子句中的目标列表达式指定别名，一种方法是直接在目标列表达式后加上空格和别名。

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