Right-click the schema you want to modify and select Add Tables from the context menu. The Database Identification wizard appears.
Walk through the wizard and select the tables, views, and procedures you want to include in the schema.
Select the tables, views, and procedures you want to add to your the schema and click the Add button. To add all the available tables, views, or procedures, click the Add All button.
Use the Remove button to delete a table, view, or procedure that you added to the Tables for Schema list. To remove all tables, views, or procedures and start over, click the Remove All button.
If you have existing statements built and you want to edit them, do the following:
Create a new schema. How?
From the Edit menu, select Edit SQL.
Enter your SQL statement.
NOTE: The Table Diagram panel will display "SQL Statement is edited text" for custom statements, and will not allow you to graphically edit the schema.