CHECK Conditions on Columns

A CHECK condition can be applied as a constraint on the table, instead of on a single column.

Such CHECK conditions typically specify that two values in a row being entered or modified have a proper relation to each other. Column CHECK conditions are held individually in the system tables, and can be replaced or deleted individually. This is more flexible behavior, and CHECK conditions on individual columns are recommended where possible.

• Adding a Check Condition in Interactive SQL
  You can add a new CHECK condition to the table or to an individual column.
• Deleting a Check Condition in Interactive SQL
  You can delete a CHECK condition from an individual column.
• Replacing a Check Condition in Interactive SQL
  You can delete a CHECK condition from an individual column.