How can I use MySQL 5.x with PHP 4.x?

I am requested to support a legacy system. I needed to install PHP4 on my computer for that and also MySQL 4开发者_如何学运维.x. I couldn't find a MySQL 4.x version that installs on my computer so I thought I'd upgrade the system to MySQL 5.x. The problem is, PHP4 does not seem to work with MySQL 5.x.

I've read somewhere that something called mysqli is needed in PHP for it to be able to work with MySQL 5.x. I just couldn't quite understand whether it's something that is included in PHP5 or something I can add to PHP4.

If it's something I can add to PHP4, how?

Thanks.

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PHP4 should work mostly fine with MySQL 5. Note I'm just talking from experience, sometimes it seems the technical stuff I read on the official MySQL and PHP sites have conflicted with what I observe. For what I've done, the only thing I really needed to worry about for compatibility between the two is authentication. Make sure the MySQL account you're trying to connect with from PHP4 uses the old password encoding. You can see this yourself in the mySQL user table. I can't remember the exact numbers but passwords stored under the old format are around 16 characters hashed whereas under the new format they are significantly longer.

More info here: http://dev.mysql.com/doc/refman/5.5/en/old-client.html