How to deal with NULL values in MySQL

Null values are different than any other value in the world, you cannot use the qual operator when working with null values, query like this will not work:

How to count how many table inside a database

When first starting a project, you probably just creating a few tables inside a database, but as the project gets more mature, the application is growing and you end up having so many tables. On mysql you can count the number of tables inside a database with a special query.