In Sybase Central, the foreign key of a table appears on the Constraints tab, which is located on the right pane when a table is selected.

You create a foreign key relationship when you create the child table (that is, prior to inserting data in the child table). The foreign key relationship then acts as a constraint; for new rows inserted in the child table, the database server checks to see if the value you are inserting into the foreign key column matches a value in the primary table's primary key.

After you have created a foreign key, you can keep track of it on each table's Constraints tab in the right pane; this tab displays any foreign tables that reference the currently selected table.

To create a new foreign key (Sybase Central)

1. Connect to the database as a user with DBA authority, or as the owner of the table.

2. In the left pane, double-click Tables.

3. Right-click the table and choose New » Foreign Key.

4. Follow the instructions in the Create Foreign Key Wizard.

To delete a foreign key (Sybase Central)

1. Connect to the database as a user with DBA authority, or as the owner of the table.

2. In the left pane, double-click Tables.

3. Select the table for which you want to delete a foreign key.

4. In the right pane, click the Constraints tab.

5. Right-click the foreign key and choose Delete.

6. Click Yes.

For any given table, you can also view a list of tables that reference the table using a foreign key.

To display a list of tables that reference a given table (Sybase Central)

1. Connect to the database as a user with DBA authority, or as the owner of the table.

2. In the left pane, double-click Tables.

3. Click the table.

4. In the right pane, click the Referencing Constraints tab.