Allows you to enable or disable all constraints, specified
    constraints, a primary key, or a unique column name, as described
    in the following list. By default, table and column constraints
    added during a create table operation are enabled.

    o  DISABLE ALL CONSTRAINTS

       All table and column constraints for this table are disabled.
       No error is raised if no constraints are defined on the table.

    o  ENABLE ALL CONSTRAINTS

       All and column constraints for this table are enabled. No
       error is raised if no constraints are defined on the table.

    o  DISABLE CONSTRAINT constraint-name

       The named constraint is disabled. The named constraint must be
       a table or column constraint for the table.

    o  ENABLE CONSTRAINT constraint-name

       The named constraint is enabled. The named constraint must be
       a table or column constraint for the table.

    o  DISABLE PRIMARY KEY

       The primary key for the table is disabled.

    o  ENABLE PRIMARY KEY

       The primary key for the table is enabled.

    o  DISABLE UNIQUE (column-name)

       The matching UNIQUE constraint is disabled. The columns listed
       must be columns in the table.

    o  ENABLE UNIQUE (column-name)

       The matching UNIQUE constraint is enabled. The columns listed
       must be columns in the table.