Deletes one or more constraint definitions.  When the DELETE
 CONSTRAINT statement executes, Rdb/VMS deletes the constraint
 definition from the physical database.  If you use the PATHNAME
 qualifier when you invoke the database, DELETE CONSTRAINT also
 deletes the constraint definition from the data dictionary.

 You cannot delete a constraint when there are active transactions
 that access the relation or relations involved.

 You must execute this statement in a read/write transaction.  If
 there is no active transaction and you issue this statement, Rdb/VMS
 starts a read/write transaction implicitly.

 You cannot delete a constraint definition unless you have invoked the
 database that includes the constraint.  Other users are allowed to be
 attached to the database when you issue the DELETE CONSTRAINT
 statement.

 Example:

      DELETE CONSTRAINT EMPLOYEE_ID_EXISTS.

Additional information available:

FormatExamplesMore

 DELETE CONSTRAINT ──┬──> constraint-name ──┬──> .
                     └─────<─── , ────<─────┘

Additional information available:

constraint-name

 The name of the constraint definition you want to delete.

 Example 1

 The following example deletes a single constraint definition:

 INVOKE DATABASE PATHNAME 'PERSONNEL'
 DELETE CONSTRAINT EMP_NUM_CON.

 This statement deletes EMP_NUM_CON from the physical database and the
 data dictionary.


 Example 2

 You can also delete more than one constraint definition at once:

 INVOKE DATABASE FILENAME 'PERSONNEL'
 DELETE CONSTRAINT SAL_CON,SS_NUM_CON.

 This statement deletes the two constraint definitions from the
 physical database.

 To delete a constraint, you must have the Rdb/VMS READ privilege to
 the database and the Rdb/VMS DELETE privilege to all relations to
 which the constraint refers.