Question

我在Microsoft Access中工作。

我有两个表，生产和试剂。

Reagents
- Reagent Reference ID (text)
- Supplier (text)

Production
- Production Reference ID (text)
- C Reference ID (text) (matches Reagents.Reagent Reference ID)
- P Reference ID (text) (matches Reagents.Reagent Reference ID)

我正在尝试建立一个查询，将C和P的供应商（从试剂）链接到生产参考ID（来自生产），如下所示。

Query Output
- Production Reference ID
- C Supplier
- P Supplier

以下是我到目前为止所得到的内容，但它告诉我我错过了一名操作员。

SELECT C.Supplier as 'C Supplier', P.Supplier as 'P Supplier'
FROM Production
INNER JOIN Reagents AS C ON C.Reagent Reference ID=Production.C Reference ID
INNER JOIN Reagents AS P ON P.Reagent Reagent Reference ID=Production.P Reference ID
WHERE Production.Production Reference ID=?

提前致谢！

Answer 1

您可以尝试此方法（这是使用子查询，请注意，如果表很大，它可能会有点慢）：

SELECT Production.[Production Reference ID],
(SELECT Reagents.Supplier FROM Reagents WHERE Reagents.[Reagent Reference ID] = Production.[C Reference ID] ) as CSupplier, 
(SELECT Reagents.Supplier FROM Reagents WHERE Reagents.[Reagent Reference ID] = Production.[P Reference ID] ) as PSupplier
FROM Production;

编辑：通过一些测试，我发现它在JOIN中是如何工作的，它比方法1快得多：

SELECT C.Supplier as 'C Supplier', P.Supplier as 'P Supplier'
FROM ( Production
INNER JOIN Reagents AS C ON C.[Reagent Reference Number]=Production.[C Reference Number] )
INNER JOIN Reagents AS P ON P.[Reagent Reagent Reference Number]=Production.[P Reference Number]
WHERE Production.[Production Reference Number]=?

在查询中使用多个JOIN时，MS Access需要括号。

Answer 2

尝试将字段名封装在方括号[]上，如下所示。

SELECT C.Supplier as 'C Supplier', P.Supplier as 'P Supplier'
FROM Production
INNER JOIN Reagents AS C ON C.[Reagent Reference Number]=Production.[C Reference Number]
INNER JOIN Reagents AS P ON P.[Reagent Reagent Reference Number]=Production.[P Reference Number]
WHERE Production.[Production Reference Number]=?

SQL Access：两个表之间的多个内部联接

2 个答案: