Question

我是MySQL的新手，我尝试创建以下查询：

SELECT locations.PuP, processing_system.deposited_timedate
FROM locations
INNER JOIN employee ON employee.fk_location = location_id
INNER JOIN processing_system ON processing_system.fk_emp = employee.emp_id
WHERE processing_system.deposited_timedate BETWEEN '2020-07-08 00:00:00' AND '2020-07-08 23:59:59'

These are the tables I want to use

These are the data in the tables

该查询似乎有效，除非它仅给我表名称而不包含任何数据。有人可以帮忙解决吗？

Answer 1

基本上，您没有收到结果，因为employee表中的fk_location为空。因此，这是您表中的数据问题。你可以试试这个吗我已删除两者之间的内容，并使用了比较。

SELECT loc.Pup, psys.deposited_timedate
 FROM
    Locations AS loc
        INNER JOIN
    Employee AS emp ON emp.fk_location = loc.location_id
        INNER JOIN
    Processing_system AS psys ON psys.fk_emp = emp.emp_id
 WHERE
    psys.deposited_timedate > '2020-07-08 00:00:00'
        AND psys.deposited_timedate < '2020-07-08 23:59:59'

MySQL查询返回了一个Empyt结果集

1 个答案: