A SQL Joins is used to combine rows from two or more tables in a database which is based on the relationship between the columns in that tables. A SQL join is used with WHERE Clause of select, update and delete statements. There are types of SQL Joins which are,

1) Inner join
   a) Equi join

2) Outer join
   a) Left outer join
   b) Right outer join
   c) Full outer join

3) Self join

When we are mention our data in the table form in the database that time if we require one or more rows joining on the various tables in the same database, we are using joins. There are mainly three type of joins such as inner, outer, and self joins.