SQL使用WHERE查询联接4个表

Question

我试图将4个表连接在一起，如下图所示： https://imgur.com/a/jukJvSw

我编写的SQL查询返回除TExpiryDate之外的所有字段，并且我没有在网上遇到任何可以帮助我理解这一点的示例。请帮忙。

SELECT tbPurchaseHeader.PurchaseDate, 
       tbSupplier.CompanyName, 
       tbPurchaseDetails.UnitCost, 
       tbPurchaseDetails.Quantity, 
       tbPurchaseDetails.Bonus, 
       tbpurchasedetails.BatchID,
       tbBatch.TExpiryDate
FROM   ((tbPurchaseDetails 
       INNER JOIN tbPurchaseHeader
               ON tbPurchaseDetails.PurchaseID = tbPurchaseHeader.PurchaseID) 
        LEFT JOIN tbBatch
               ON tbPurchaseDetails.BID = tbBatch.BID)
       INNER JOIN tbSupplier 
               ON tbPurchaseHeader.SupplierID = tbSupplier.SupplierID 
WHERE  tbPurchaseDetails.ProductID = ? 
ORDER  BY tbPurchaseHeader.PurchaseDate 

Answer 1

结果BID在数据库中包含空值。我决定在其他地方建立链接以获取数据。谢谢大家让我意识到这一点。