public function addIsNullCondition($column){
        $this->conditionColumns[] = $column;
        return $this->addCondition($this->_column($column) . " IS NULL");
    }
public function addIsNullCondition($column){
        $this->conditionColumns[] = $column;
        return $this->addCondition($this->_column($column) . " IS NULL");
    }
public function addIsNullCondition ( $ column ) { $ this -> conditionColumns [ ] = $ column ; return $ this -> addCondition ( $ this -> _column ( $ column ) . " IS NULL" ) ; }
Checks if a column is null
@param string $column
@return ModelCondition
@throws \Exception
Checks if a column is null