Control the integrity of your database with constraints

A constraint is a restriction or limitation placed on a file to ensure that the data in your database remains consistent as you add, change, and remove records. These topics describe how to use constraints to ensure data consistency.

Primary key and unique constraints can be used as the parent key when adding a referential constraint.

• Set up constraints for your database
  You can use physical file constraints to control the integrity of the data that is maintained in your database. You can also add constraints using iSeries™ Navigator.
• Remove unique, primary key, or check constraints
  The Remove Physical File Constraint (RMVPFCST) command allows you to remove a physical file constraint. The full effects of the command depend on the type of constraint you remove and how it is used.
• Work with a group of constraints
  The Work with Physical File Constraints (WRKPFCST) command allows you to display and work with a list of the constraints.
• Unique constraints
  Unique constraints act as controls in a database to ensure that rows are unique.
• Primary key constraints
  A primary key constraint is a unique key with special attributes that make the key the primary access path for the file.
• Check constraints
  You use check constraints to maintain limits on field values so that they conform to your database requirements.