Loop over all columns of a table

I want to loop over all the columns of a few tables and run various SQL queries like the number of missing values, min, max, etc. and write results to a new table. However, I don't know how I can loop over all the columns of all the tables. Can you guide how I can write a procedure for that or any other way?

I have MariaDB 10.4 Series and Heidi SQL version 10.2.0.5599.