如何使用union all查询出重复数据

使用UNION ALL关键字可以查询出重复数据。UNION ALL是将两个查询语句的结果合并输出，不去除重复数据。在使用UNION ALL进行联合查询时，需要确保两个查询语句的字段顺序、字段名称和字段类型都一致。例如，可以使用以下语法进行UNION ALL查询：

SELECT 字段列表 FROM 表A
UNION ALL
SELECT 字段列表 FROM 表B

这样就可以将表A和表B的查询结果合并输出，包括重复的数据。
#### 引用[.reference_title]
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