public function where($column, $expression = null, $value = null)
    {
        return $this->doWhere(self::AND_WHERE, $column, $expression, $value);
    }
public function where($column, $expression = null, $value = null)
    {
        return $this->doWhere(self::AND_WHERE, $column, $expression, $value);
    }
public function where ( $ column , $ expression = null , $ value = null ) { return $ this -> doWhere ( self :: AND_WHERE , $ column , $ expression , $ value ) ; }
Add a 'where' clause to the query.

@param string $column     The column name
@param string $expression The comparison, e.g. '=' or '<'
@param string $value      The value
Add a where clause to the query .