The module can write data within GNU Radio flowgraphs to MySQL databases using the GNU Radio message system. Possible use-cases are events with time-stamps or samples from a measurement system. Care about the data rate so that the MySQL database can process the input.
In the following, the example setup uses MariaDB run with a Docker image. Any other setup and MySQL database should work as well (but Docker is awesome!).
First download the latest docker image of MariaDB with 'docker pull mariadb'. You have to start the docker service with a command like 'systemctl enable docker.service' (that depends on your system). Then run the latest Docker image with 'docker run --name mariadb_instance_name -e MYSQL_ROOT_PASSWORD=my_password -d mariadb:latest'. See [0] for more information.
You can start and stop this instance from now on with 'docker start mariadb_instance_name' and 'docker stop mariadb_instance_name'.
We'll connect to the database via the IP address. This can be taken from the output of 'docker inspect mariadb_instance_name | grep IPAddress'. Now you can connect to the database as root with 'mysql -u root -p -h '. The password has been set with MYSQL_ROOT_PASSWORD=my_password.
Next step is creating a database and a table, which matches your desired output data of the GNU Radio flowgraph. Use 'CREATE DATABASE my_db;' to create a new database and 'USE my_db;' to change to it. A new table can be created with 'CREATE TABLE my_table (id int, value float);'. Here, you have to set the desired data types, which matches the message in the GNU Radio flowgraph (more about this later).
Now create a new user with 'CREATE USER my_user' and give him rights to write to the previously created table with 'GRANT INSERT ON my_table TO my_user;'.
Exit the MySQL terminal and reenter as the new user with 'mysql -u my_user -p -h '. There is no password for the user (so the -p option is actually not necessary), which can be set with 'SET PASSWORD = PASSWORD('my_password');'.
Now, the MySQL database is fully set up to write with gr-sql to it out of a GNU Radio flowgraph.