同时查询特定日期范围的多个表

Question

我有三个相同的table：

gradbusdb.user
gradedudb.user
gradtheologydb.user

在每个 table 中，我有 YYYY-MM-DD 格式的 email 和 submited_date。我的最终目标是同时查询所有三个 table，但是当我在 email 和 submited_date 的 3 个 table 之间执行 UNION 时它忽略我的 WHERE 条件并显示所有结果的列。

我目前的查询如下：

SELECT email, submited_date FROM gradbusdb.user 
UNION
SELECT email, submited_date FROM gradedudb.user
UNION
SELECT email, submited_date FROM gradtheologydb.user
WHERE submited_date BETWEEN '2016-02-01' AND '2016-02-29'
ORDER BY submited_date ASC

我不确定我在这里做错了什么，但我需要我的查询只显示日期范围内的结果。

Answer 1

您应该对联合的每个查询使用 WHERE

SELECT email, submited_date FROM gradbusdb.user 
WHERE submited_date BETWEEN '2016-02-01' AND '2016-02-29'
UNION
SELECT email, submited_date FROM gradedudb.user
WHERE submited_date BETWEEN '2016-02-01' AND '2016-02-29'
UNION
SELECT email, submited_date FROM gradtheologydb.user
WHERE submited_date BETWEEN '2016-02-01' AND '2016-02-29'

ORDER BY submited_date ASC

同时查询特定日期范围的多个表

Query Multiple Tables For Specific Date Range Simultaneously

mysql

union