如何在sql查询中使用大小写

Question

我的查询位于

之下

SELECT *, 
CASE WHEN SUBSTRING(controlId,1,1) = 'M' THEN (select fullname from master as controler 
where Regular.controlId = Master.MasterId)

WHEN SUBSTRING(controlId,1,1) = 'A' THEN (select fullname from Admin as controler 
where Regular.controlId = Master.AdminId)
END AS controler
FROM Regular
INNER JOIN Master ON Regular.ControlId = Master.MasterId 
INNER JOIN Admin ON Regular.ControlId = Admin.AdminId
Where (Regular.active=0)

我的表格

我的常规数据

我的主表

我的管理员表数据

我想从每一行的相关表中获取全名，但使用上面的代码却没有给出任何结果....

Answer 1

这些数据似乎很难正常化，并且问题中的信息不足以确定发生了什么，但我怀疑你的联接是错误的，你真的需要使用LEFT联接而不是INNER联接。然后你可以使用COALESCE（）函数而不是CASE子句：

SELECT r.*, COALESCE(m.FullName, a.FullName, r.FullName) FullName 
FROM Regular r
LEFT JOIN Master m ON r.ControlId = m.MasterId 
LEFT JOIN Admin a ON r.ControlId = a.AdminId
WHERE r.active=0

Answer 2

我无法使用INNER JOIN s

INNER JOIN Master ON Regular.ControlId = Master.MasterId 
INNER JOIN Admin ON Regular.ControlId = Admin.AdminId

列Regular.ControlId不能同时存在于Master和Admin

列中

SELECT *, 
CASE WHEN SUBSTRING(controlId,1,1) = 'M' THEN (select fullname from master as controler 
where Regular.controlId = Master.MasterId)

WHEN SUBSTRING(controlId,1,1) = 'A' THEN (select fullname from Admin as controler 
where Regular.controlId = Master.AdminId)
END AS controler
FROM Regular
Where (Regular.active=0)

Answer 3

也许是因为内联。尝试更改为：

    SELECT *, 
    CASE WHEN SUBSTRING(controlId,1,1) = 'M' THEN (select top 1 fullname from Master
    where Regular.controlId = Master.MasterId)

    WHEN SUBSTRING(controlId,1,1) = 'A' THEN (select top 1 fullname from Admin
    where Regular.controlId = Admin.AdminId)
    END AS controler
    FROM Regular
    Where (Regular.active=0)