1. A SQL join clause combines columns from … 1. A SQL join clause combines columns from one or more tables in a relational database. It creates a set that can be saved as a table or used as it is. A JOIN is a means for combining columns from one (self-table) or more tables by using values common to each.ore tables by using values common to each.
, 2. A JOIN clause is used to combine rows from two or more tables, based on a related column between them.