Online Documentation for SQL Manager for InterBase/Firebird
Creating/editing unique key
The Unique section of the Constraints dialog allows you to specify UNIQUE constraint definition.
Name
Name of the UNIQUE constraint; the constraint name must be unique within the table.
Fields for unique key
To include field(s) in the unique key, you need to move it from the Available Fields list to the Included Fields list. Use the buttons or drag-and-drop operations to move the fields from one list to another.