mysql - 更改数据库结构：需要 SQL 查询

Question

我有两张桌子：

connections
id | publisherId | authorId

和

books
id | connectionId | title

我想合并这些表来只得到一个表：

books
id| publisherId | authorId | title

我怎样才能只用一个 SQL 查询来做到这一点？

Answer 1

CREATE TABLE newtable
SELECT b.id, c.publisherId, c.authorID, b.title
FROM books b
INNER JOIN connections c
on c.id = b.connectionId

未经测试，但这应该可以。我假设您需要 books 表中的 ID，否则您需要 c.id 而不是 b.id。

然后您可以删除旧表并将其重命名为您想要的任何名称。

Answer 2

CREATE TABLE connections_books 
SELECT books.id as id, 
       connections.publisherId as publisherId, 
       connections.authorId as authorId, 
       books.title as title 
FROM books join connections on books.connectionId = connections.id;

首先使用以下select部分测试查询：

SELECT books.id as id, 
       connections.publisherId as publisherId, 
       connections.authorId as authorId, 
       books.title as title 
FROM books join connections on books.connectionId = connections.id;

一旦这为您提供了所需的内容，请继续创建表格。

确保新表中的列名正确非常重要。使用 select 语句测试以确保您的列名是您想要的。如果要更改列名，请更改as ...每个选定列的名称。