public function get_sql() : string {
		if ( empty( $this->columns_to_select ) ) {
			// this should be the default behavior
			$this->columns_to_select = [ '*' ];
		}

		$from = ' FROM ' . implode( ', ', $this->from ) . ' ';

		if ( ! empty( $this->joins ) ) {
			$from .= $this->joins;
		}

		$from  .= 'WHERE ' . $this->where_clause;
		$select = 'SELECT ' . implode( ', ', $this->columns_to_select ) . $from;

		if ( ! empty( $this->group_by ) ) {
			$select .= 'GROUP BY ' . implode( ', ', $this->group_by ) . ' ';
		}

		if ( $this->order_by !== '' ) {
			$select .= 'ORDER BY ' . $this->order_by . ' ';
		}

		$select .= 'LIMIT ' . $this->limit;

		if ( $this->offset !== '' ) {
			$select .= ' OFFSET ' . $this->offset;
		}

		return $select;
	}