Description of the illustration constraints.gif

This image is a screenshot of the Edit Table page, with the Constraints subpage displayed. The Constraints subpage contains the following controls and data:

At the upper right-hand corner, ordered from left to right, are a list and an Add button. The list contains types of constraints, and currently shows the type PRIMARY.
Below these controls is a table of existing constraints for the PURCHASE_ORDERS table. The table has the following columns: Select, Name, Type, Table Columns , Disabled, Deferrable , Initially Deferred , Validate RELY, Check Condition, Referenced Schema, and Referenced Table. (There are more columns that are not shown on this image.) The table has four rows. Three rows are CHECK constraints, where each enforces a NOT NULL rule for a different column. The fourth row is a PRIMARY constraint that indicates that PO_NUMBER is the primary key. All constraints have system-assigned names.
Just above the table of existing constraints are two buttons, ordered from left to right: Edit and Delete.