How to Execute Cross Database Queries in PHP?

Cross Database Queries in PHP: Breaking the Barriers

In the previous episode, constructing cross database queries in MySQL was made possible. However, translating this knowledge to PHP presented a roadblock due to limitations with mysql_select_db.

Options and Limitations

The options available in PHP are:

• Use mysql_select_db: Restricts usage to one database per session. Attempting to use cross database references fails.
• Avoid mysql_select_db: Requires specifying the database for every query, which is tedious and impractical.

The Solution

To overcome these limitations and perform cross database queries in PHP, we can leverage the following method:

Prerequisites

This approach requires that both databases reside on the same host. If they are on different hosts, direct joins are not possible. In this case, you can execute two separate queries:

By utilizing this method, you can effortlessly perform cross database queries in PHP, expanding the capabilities of your database interactions.

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