SQL Exporter is used to test your SQL queries before deploying them. Use this link to download it. (I downloaded the darwin-amd64 version)
Usage of SQL Exporter
Open up the folder in your preferred IDE for ease of access and change the sql_exporter.yml file to accommodate for the collector that you will be using. Also make sure to have the correct data source.
Inside the [collector_name].collector.yml file, create your desired metrics.
Make sure to double check the correct syntax for the yaml file, as it is indentation sensitive.
Highly recommend using a database querying workbench such as DBeaver or MySQL Workbench to quickly test your SQL queries, as this will also allow you to preview what data you can expect to receive.
When your desired query is made, run the sql_exporter file in a terminal and observe any errors that may occur. If it runs successfully, a port will be displayed on screen.
Note that the values field is mandatory. Structure your SQL query around this.
Use this port number and go to http://localhost:[PortNumber]. Here, you can review whether your metrics got picked up correctly, and if they didn't, an error will be printed to the terminal where you have sql_exporter running. Analyse and fix this error if needed.
Once your metric has been checked and it works correctly when using sql_exporter, you can move on to the next step.