Adding or Dropping Constraints
To drop a constraint, the DB Access Module for MySQL requires the constraint type as well as the constraint name. To drop a constraint, use the RWDBTable::dropConstraint() method that takes a constraint object rather than a constraint name.
NOTE: Because the module does not support check constraints, adding and dropping check constraints using the RWDBTable::addConstraint() and RWDBTable::dropConstraint() API is not supported.