Hi,

> What is the difference and which one is better?
>
> Alter Table REF_STA add Primary Key (STA_CDE);

This creates a primary key constraint, with a system generated name
(something like INTEG_nn).

> Alter Table REF_STA add Constraint pk_REF_STA Primary Key (STA_CDE);

This creates a named primary key constraint which you can recognize
and, since Firebird 1.5, an underlying index with the same name.

Martijn Tonies
Database Workbench - tool for InterBase, Firebird, MySQL, NexusDB, Oracle &
MS SQL Server
Upscene Productions
http://www.upscene.com
My thoughts:
http://blog.upscene.com/martijn/
Database development questions? Check the forum!
http://www.databasedevelopmentforum.com