public function where($column, $operator, $value, $filter = false)
    {
        return $this->constraint(__FUNCTION__, $column, $operator, $value, $filter);
    }
public function where($column, $operator, $value, $filter = false)
    {
        return $this->constraint(__FUNCTION__, $column, $operator, $value, $filter);
    }
public function where ( $ column , $ operator , $ value , $ filter = false ) { return $ this -> constraint ( __FUNCTION__ , $ column , $ operator , $ value , $ filter ) ; }
Adds where clause

@param string $column
@param string $operator
@param string $value
@param boolean $filter Whether to filter by empty value
@return \Krystal\Db\Sql\Db
Adds where clause