question: public void addConstraintCommand ( DefineCommand command ) { if ( command instanceof CreateIndex ) { constraintCommands . add ( command ) ; } else { AlterTableAddConstraint con = ( AlterTableAddConstraint ) command ; boolean alreadySet ; if ( con . getType ( ) == CommandInterface . ALTER_TABLE_ADD_CONSTRAINT_PRIMARY_KEY ) { alreadySet = setPrimaryKeyColumns ( con . getIndexColumns ( ) ) ; } else { alreadySet = false ; } if ( ! alreadySet ) { constraintCommands . add ( command ) ; } } }
target:  Add a constraint statement to this statement. The primary key definition is one possible constraint statement.