code/libraries/joomlatools/library/database/query/select.php
public function columns($columns = array())
    {
        foreach ((array) $columns as $key => $value)
        {
            if (is_string($key)) {
                $this->columns[$key] = $value;
            } else {
                $this->columns[] = $value;
            }
        }

        return $this;
    }
public function columns($columns = array())
    {
        foreach ((array) $columns as $key => $value)
        {
            if (is_string($key)) {
                $this->columns[$key] = $value;
            } else {
                $this->columns[] = $value;
            }
        }

        return $this;
    }
public function columns ( $ columns = array ( ) ) { foreach ( ( array ) $ columns as $ key => $ value ) { if ( is_string ( $ key ) ) { $ this -> columns [ $ key ] = $ value ; } else { $ this -> columns [ ] = $ value ; } } return $ this ; }
Build a select query

@param  array|string $columns A string or an array of column names
@return $this
Build a select query