用PHP同时连接和查询两个Mysql数据库

Question

I'm intending to develope a web that interacts with three different Mysql databases in the same server. User and password are the same in all three databases.
I want to use mysqli in procedural mode.
Some times I want to query just one databse, some times two of them, whatever.
What would it be the best way to connect with two of them and then, say, join two tables belonging to different databases?
Thanks in advanced!

Answer 1

If the databases all reside in the same server, you can query any table in any database at any time that you have access to by prefixing it with the database name:

SELECT *
  FROM database1.table1
  JOIN database2.table2 ON ...

If the databases are on two different servers or need different access rights, there's no way to do this.