An SQL join clause – corresponding to a join operation in relational algebra – 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-join) or more tables by using values common to each.
They can be used to unite some or all of the data from two or more tables into one comprehensive structure. You can perform joins using the diagram pane. To do this:
- Click the value(s) from a database Field List.
- Drag it to the required field.
- When the cursor takes shape, release the click.
The join will be indicated as an arrow symbol between the selected fields.
Figure 5: Performing Joins
Note: When you select two tables, Intellicus may automatically create join between the two. This would happen because a Primary Key – Foreign Key relation was already created in the database and Enable Autolink Foreign Key check box (Options > Custom Design) is selected. In this case, respective condition will also be added in WHERE clause of the query.
If Enable Autolink Foreign Key check box is clear (not selected), Joins are not automatically created.
Removing a Join
To remove a join condition, select a join condition by clicking under the where clause and press <delete> on the keyboard.
Figure 6: Removing a Join
The join will be removed.