如何使用MySQL在单个查询中查询两个不同的数据库？

问题描述：

I have two websites that post news information. I just got a request to make a single page for one of the sites that shows the mixed results from both sites. They are located on the same server and the tables are close to identical, but I am having problems figuring out how to combine the two queries. The postings need to be sorted by date, title when all is said and done.

For arguments sake, a simplified form of the tables is

DB 1, TABLE Clips1 (PK_ID, DateToShow, Title, Description)

DB 2, TABLE Clips2 (PK_ID, DateToShow, Title, Description)

So the single query would hit both databases (usernames and passwords are different currently), or two queries and some kind of combination that would keep the date and titles sorted.

我有两个网站发布新闻信息。我刚收到一个请求，要求为其中一个站点制作一个页面，显示两个站点的混合结果。它们位于同一台服务器上，并且表格几乎完全相同，但我在弄清楚如何组合这两个查询时遇到了问题。当完成所有操作时，帖子需要按日期，标题进行排序。 p>

为了论证，表的简化形式是 p>

DB 1，TABLE Clips1（PK_ID，DateToShow，Title，Description） p>

DB 2，TABLE Clips2（PK_ID，DateToShow，Title，Description） p>

因此，单个查询将同时命中两个数据库（用户名和密码当前不同），或者两个查询以及某种组合可以保持日期和标题的排序。 p> div>

答

IF you can use a single connection for the query, it is trivial.

You say that the schemas are on the same server, so with the appropriate permissions this shouldn't be a problem.

The general syntax for this is:

SELECT schemaA.table.column
FROM schemaA.table
UNION
SELECT schemaB.table.column
FROM schemaB.table

You can even do JOINs, just remember to specify the appropriate schema for every table and field reference.

如何使用MySQL在单个查询中查询两个不同的数据库？

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