A SQL Join clause is a way to retrieve information from two or more tables in a database. When a database programmer wants to do a join command, they will type about the databases they want to get information from, and the type of join they want to use. There are five types of joins. A normal codice_1, which is also called an codice_2, a codice_3, acodice_4, acodice_5 and codice_6.