mysql - SQL查询忽略条件

Question

所以我试图“列出由作者 Gale 撰写并由 Pocket Books 打印的所有书籍”

我的数据库表如下

Table: author 
authorNumber, authorName
         01         Gale
         02         Ben
Table: book
bookCode,  bookTitle,     publishCode
     189   Press & Trash  PB
    3743   Ecommerce      PB

Table: publisher
publisherCode, publisherName
      PB        Pocket Books
      BB        Batman Books

Table: wrote
bookCode,  authorNumber
     189     01
     3743    02 

这是我的查询，它忽略了我的 Gale 条件，只是获取 Pocket Books 出版的所有书籍，有什么帮助吗？

SELECT bookTitle
FROM Book B, Wrote BC, Author, Publisher PC
WHERE B.bookCode = BC.bookCode
AND B.publisherCode = PC.publisherCode
AND authorName ='Gale'
AND publisherName ='Pocket Books'
GROUP BY bookTitle;

Answer 1

您忘记添加author的连接条件。您最好使用显式连接语法，这使得它更加明显。

SELECT B.bookTitle
FROM Book B
join Wrote BC on B.bookCode = BC.bookCode
join Author A on BC.authorNumber = A.authorNumber
join Publisher PC on B.publisherCode = PC.publisherCode
WHERE A.authorName ='Gale'
AND PC.publisherName ='Pocket Books'
GROUP BY B.bookTitle

而且您也不需要分组。