SQL选择多个表

Question

存储货币换算值的数据库。这些值将根据vb.net程序中的输入日期添加到文本框中。

鉴于三个表

GBP (table) 
Date (pk)
GUSD
GEUR

USD(table) 
Date (pk)
UGBP
UEUR

EUR(table) 
Date (pk)
EUSD
EGBP

如何选择除日期以外的所有3个表中的所有记录？

我设法从一张桌子中选择记录。

Dim sql As String = "SELECT TOP 1 GEUR,GUSD FROM GBPtb WHERE Date= ?"

Design view of the application

Answer 1

由于您提供的信息有限，我猜您可能需要以下内容

SELECT 1.0 as GBP, GUSD as USD, GEUR as EUR FROM GBP WHERE Date = ?
UNION ALL
SELECT UGBP as GBP, 1.0 as USD, UEUR as EUR FROM USD WHERE Date = ?
UNION ALL
SELECT EGBP as GBP, EUSD as USD, 1.0 as EUR FROM EUR WHERE Date = ?