You use a join to combine data from different tables into a single result set. Joins most commonly use foreign key relationships. Some important points about joins include:
- Joins are created through instructions in the SELECT clause.
- Joins connect two or more tables by using a join operator.
- Joins exist only for the duration of that query.
- Joins do not make changes to any database tables.
You use the JOIN keyword to specify the tables you want to join and how to join the tables. You use the ON keyword to specify the common columns between the two tables—the columns to use for the join. If the columns have the same names in both tables, you must specify the columns as table name.column.name.