code: public void putNull(String key) {
  		if (this.compiledStatement != null) {
  			compiledStatement.bindNull(compiledStatementBindIndex++);
  		} else if (values != null) {
  			values.putNull(key);
  			return;
  		}
  
  		names.add(key);
  		// values.putNull(key);
  		args.add(null);
  		valueType.add(ParamType.NULL);
  	}
docs: Adds a null value to the set.
  
  @param key
  the name of the value to make null