从5个表格中获取数据

Question

我有5个表格：tblbook，tblauthor，tblpublisher，tblauthorbook，tblbookpublisher

• tblbook具有以下列：
  • BookID，
  • Barcode，
  • ISBN，
  • BookSection和
  • BookCopyNumber

• tblauthor：

  • AuthorID，
  • AuthorName

• tblpublisher

  • publisherID
  • publishername

• tblauthorbook

  • AuthorID
  • BookID
• tblbookpublisher
  • publisherID
  • BookID

我需要做的是在列表视图中显示与vbnet中输入的条形码编号相等的所有书籍，以及它们的authorname和publisher。

我对如何执行此操作感到困惑，这是我尝试过的查询：

"Select tblbook.BookID, 
   tblbook.BookTitle,
   tblbook.BookSection,
   tblauthorbook.AuthorID,
   tblauthorbook.BookID,
   tblauthor.AuthorID,
   tblauthor.AuthorName,
   tblbookpublisher.PublisherID,
   tblbookpublisher.BookID,
   tblpublisher.PublisherID,
   tblbook.AcSecCode 
 from tblbook, 
   tblauthorbook, 
   tblauthor, 
   tblbookpublisher, 
   tblpublisher 
 where tblbook.Barcode = '" & txtbarcode.Text & "' 
   and tblbook.BookID = tblauthorbook.BookID 
   and tblauthorbook.AuthorID = tblauthor.AuthorID 
   and tblbook.BookID = tblbookpublisher.BookID 
   and tblbookpublisher.PublisherID = tblpublisher.PublisherID"

没有错误，但它在列表视图中未显示任何内容，因此我的查询一定是错误的。有人可以帮助我如何正确查询吗？预先谢谢你

Answer 1

手动尝试此查询，并检查其是否返回内容。

外键之一可能为空。
通过使用LEFT JOIN，可以很容易地在结果中注意到这一点。

select 
 b.BookID, b.BookTitle, b.BookSection,
 ab.AuthorID, ab.BookID,
 a.AuthorID, a.AuthorName,
 bp.PublisherID, bp.BookID,
 p.PublisherID,
 b.AcSecCode
from tblbook b
left join tblauthorbook ab on ab.BookID = b.BookID 
left join tblauthor a on a.AuthorID = ab.AuthorID 
left join tblbookpublisher bp on bp.BookID = b.BookID 
left join tblpublisher p on p.PublisherID = bp.PublisherID
where b.Barcode = @YourBarCode

但是首先替换或声明并设置@YourBarCode变量