There are a number of different joins, some of which are listed below. These are included for reference only.
| Join | a relational operation that causes two or more tables with a common domain to be combined into a single table or view |
| Equi-join | a join in which the joining condition is based on equality between values in the common columns; common columns are duplicated in the result table |
| Natural join | an equi-join in which one of the duplicate columns is eliminated in the result table |
| Outer join | a join in which rows that do not have matching values in common columns are nonetheless included in the result table (as opposed to inner join, in which rows must have matching values in order to appear in the result table) |
| Union join | includes all columns from each table in the join, and an instance for each row of each table |