Query Autocomplete example as follows. This should give you an idea of how to setup a query based autocomplete usage.

Query:Value Column: id
Label Column: username
Minimum Length: 3

This will allow autocomplete selection of a user id searching by username. I cannot help you with your custom query, sorry. You'll need to figure that part out yourself and ideally should test it in phpmyadmin for faster checking if your query is working and providing the expected results as well as performance testing to see if you need additional indexes. Be careful when using wildcard % in LIKE usages as indexes cannot be used with the search starts with % (notice above it's after to support partial matches).

That can happen when the value and the label don't match. So for example the below would fail with strict mode.


But the below would work since we're also checking the value that's being stored.


In my example I'm typing out a username to find a user id. The user id what is stored. So you end up in a situation where what I searched by and what I stored isn't the same. Strict mode doesn't really cover that scenario so you have to do the above OR you can use Query Validation and validate it there with a custom validation rule.

It's possible your query is erroring. Enable debug mode and maximum error reporting in Joomla global configuration then retry and see if any errors output. The above works fine in my tests, but am also working on a clean up release for CB Query Field to improve the internal code to be more strict. That should be available today so issue might already be fixed if this is a bug.