Error establishing database connection – config file is fine

I have a multisite WP site that was up and running fine and then the “Error establishing a database connection” message started to appear. The wp-config.php file checks out.

When I go to log in at wp-admin I get the message:

“one or more database tables are unavailable. The database may need to be repaired”.

So I set the config file to allow repairs. WP runs the repairs and comes back saying the tables have been fixed. I still get the database connection error. I even repaired all the tables in phpmyadmin and it’s still not working.

I can browse the database in phpmyadmin too. So it looks like it’s okay.

I have gone to great lengths to get this back online including the following:
– fresh install of WP with a new database
– replaced the contents of the new database with a back up of the old database
This resulted in the connection error.

This leads me to believe there’s something wrong with the content in the database. Since I can’t connect, I can’t run debug or anything to begin to troubleshoot it.

Any insights would be greatly appreciated.

I’m fairly proficient at WP and setting these things up and knowledgable when it comes to Unix admin. Databases though, aren’t my thing.

Thanks in advance.