c# - 嵌套子查询从多个表中进行选择

Question

我有三张桌子：

Years (YearId,Year)
Months (MonthID,Month)
Date (DateID,YearID,MonthID)
Client (CLientID,ClientName)
Payment (PayID,ClientID,DateID,Amount)

我想将 DataGridView 填写为：

Client Name, Amount, Year, Month 

我使用了这个语句，但它不起作用：

Select * From (select Year From Years Where YearID = (Select YearId From Date Where dateID = (Select DateID From Payment))),(Select Month From Months Where Monthid = (Select MonthID From Date Where dateID = (Select DateID From Payment))),(Select ClientName From Client Where ClientID = (Select ClientID From Payment),(Select amont From Payment)

Answer 1

听起来你只是想使用INNER JOINs：

SELECT C.ClientName,
    P.Amount,
    Y.Year,
    M.Month
FROM Payment P
    INNER JOIN Client C 
        ON P.ClientID = C.ClientID
    INNER JOIN Date D 
        ON P.DateId = D.DateId
    INNER JOIN Years Y
        ON D.YearId = Y.YearId
    INNER JOIN Months M
        ON D.MonthId = M.MonthId

请参阅下文以获得良好的视觉表示JOINs：

JOINS 的可视化表示