n is either 1 or 0. The default value is 0.
When DDLNo311 is enabled (n = 1), when an attempt is made to ADD a foreign key, even if a key of that name already exists, InterSystems IRIS® data platform suppresses the SQLCODE -311 error.
For further details, refer to the ALTER TABLE command.
Changing This Parameter
On the SQL page of the Management Portal (System Administration > Configuration > SQL and Object Settings > SQL), select Ignore redundant DDL statements to suppress redundant SQLCODE errors.
You can also change DDLNo311 with the Config.SQL class (as described in the class reference) or by editing the CPF in a text editor (as described in the Editing the Active CPF section of the “Introduction to the Configuration Parameter File” chapter in this book).