Strip leading 'AND'.
			$this->sql_clauses['where']['meta_query'] = preg_replace( '/^\s*AND\s*/', '', $this->meta_query_clauses['where'] );

			if ( ! $this->query_vars['count'] ) {
				$groupby = "{$wpdb->blogs}.blog_id";
			}
		}

		$where = implode( ' AND ', $this->sql_clauses['where'] );

		$clauses = array( 'fields', 'join', 'where', 'orderby', 'limits', 'groupby' );

		/**
		 * Filters the site query clauses.
		 *
		 * @since 4.6.0
		 *
		 * @param string[]      $clauses An associative array of site query clauses.
		 * @param WP_Site_Query $query   Current instance of WP_Site_Query (passed by reference).
		 */
		$clauses = apply_filters_ref_array( 'sites_clauses', array( compact( $clauses ), &$this ) );

		$fields  = isset( $clauses['fields'] ) ? $clauses['fields'] : '';
		$join    = isset( $clauses['join'] ) ? $clauses['join'] : '';
		$where   = isset( $clauses['where'] ) ? $clauses['where'] : '';
		$orderby = isset( $clauses['orderby'] ) ? $clauses['orderby'] : '';
		$limits  = isset( $clauses['limits'] ) ? $clauses['limits'] : '';
		$groupby = isset( $clauses['groupby'] ) ? $clauses['groupby'] : '';

		if ( $where ) {
			$where = 'WHERE ' . $where;
		}

		if ( $groupby ) {
			$groupby = 'GROUP BY ' . $groupby;
		}

		if ( $orderby ) {
			$orderby = "ORDER BY $orderby";
		}

		$found_rows = '';
		if ( ! $this->query_vars['no_found_rows'] ) {
			$found_rows = 'SQL_CALC_FOUND_ROWS';
		}

		$this->sql_clauses['select']  = "SELECT $found_rows $fields";
		$this->sql_clauses['from']    = "FROM $wpdb->blogs $join";
		$this->sql_clauses['groupby'] = $groupby;
		$this->sql_clauses['orderby'] = $orderby;
		$this->sql_clauses['limits']  = $limits;

		$this->request = "
			{$this->sql_clauses['select']}
			{$this->sql_clauses['from']}
			{$where}
			{$this->sql_clauses['groupby']}
			{$this->sql_clauses['orderby']}
			{$this->sql_clauses['limits']}
		";

		if ( $this->query_vars['count'] ) {
			return (int) $wpdb->get_var( $this->request );
		}

		$site_ids = $wpdb->get_col( $this->request );

		return array_map( 'intval', $site_ids );
	}

	/**
	 * Populates found_sites and max_num_pages properties for the current query
	 * if the limit clause was used.
	 *
	 * @since 4.6.0
	 *
	 * @global wpdb $wpdb WordPress database abstraction object.
	 */
	private function set_found_sites() {
		global $wpdb;

		if ( $this->query_vars['number'] && ! $this->query_vars['no_found_rows'] ) {
			/**
			 * Filters the query used to retrieve found site count.
			 *
			 * @since 4.6.0
			 *
			 * @param string        $found_sites_query SQL query. Default 'SELECT FOUND_ROWS()'.
			 * @param WP_Site_Query $site_query        The `WP_Site_Query` instance.
			 */
			$found_sites_query = apply_filters( 'found_sites_query', 'SELECT FOUND_ROWS()', $this );

			$this->found_sites = (int) $wpdb->get_var( $found_sites_query );
		}
	}

	/**
	 * Used internally to generate an SQL string for searching across multiple columns.
	 *
	 * @since 4.6.0
	 *
	 * @global wpdb $wpdb WordPress database abstraction object.
	 *
	 * @param string   $search  Search string.
	 * @param string[] $columns Array of columns to search.
	 * @return string Search SQL.
	 */
	protected function get_search_sql( $search, $columns ) {
		global $wpdb;

		if ( false !== strpos( $search, '*' ) ) {
			$like = '%' . implode( '%', array_map( array( $wpdb, 'esc_like' ), explode( '*', $search ) ) ) . '%';
		} else {
			$like = '%' . $wpdb->esc_like( $search ) . '%';
		}

		$searches = array();
		foreach ( $columns as $column ) {
			$searches[] = $wpdb->prepare( "$column LIKE %s", $like );
		}

		return '(' . implode( ' OR ', $searches ) . ')';
	}

	/**
	 * Parses and sanitizes 'orderby' keys passed to the site query.
	 *
	 * @since 4.6.0
	 *
	 * @global wpdb $wpdb WordPress database abstraction object.
	 *
	 * @param string $orderby Alias for the field to order by.
	 * @return string|false Value to used in the ORDER clause. False otherwise.
	 */
	protected function parse_orderby( $orderby ) {
		global $wpdb;

		$parsed = false;

		switch ( $orderby ) {
			case 'site__in':
				$site__in = implode( ',', array_map( 'absint', $this->query_vars['site__in'] ) );
				$parsed   = "FIELD( {$wpdb->blogs}.blog_id, $site__in )";
				break;
			case 'network__in':
				$network__in = implode( ',', array_map( 'absint', $this->query_vars['network__in'] ) );
				$parsed      = "FIELD( {$wpdb->blogs}.site_id, $network__in )";
				break;
			case 'domain':
			case 'last_updated':
			case 'path':
			case 'registered':
			case 'deleted':
			case 'spam':
			case 'mature':
			case 'archived':
			case 'public':
				$parsed = $orderby;
				break;
			case 'network_id':
				$parsed = 'site_id';
				break;
			case 'domain_length':
				$parsed = 'CHAR_LENGTH(domain)';
				break;
			case 'path_length':
				$parsed = 'CHAR_LENGTH(path)';
				break;
			case 'id':
				$parsed = "{$wpdb->blogs}.blog_id";
				break;
		}

		if ( ! empty( $parsed ) || empty( $this->meta_query_clauses ) ) {
			return $parsed;
		}

		$meta_clauses = $this->meta_query->get_clauses();
		if ( empty( $meta_clauses ) ) {
			return $parsed;
		}

		$primary_meta_query = reset( $meta_clauses );
		if ( ! empty( $primary_meta_query['key'] ) && $primary_meta_query['key'] === $orderby ) {
			$orderby = 'meta_value';
		}

		switch ( $orderby ) {
			case 'meta_value':
				if ( ! empty( $primary_meta_query['type'] ) ) {
					$parsed = "CAST({$primary_meta_query['alias']}.meta_value AS {$primary_meta_query['cast']})";
				} else {
					$parsed = "{$primary_meta_query['alias']}.meta_value";
				}
				break;
			case 'meta_value_num':
				$parsed = "{$primary_meta_query['alias']}.meta_value+0";
				break;
			default:
				if ( isset( $meta_clauses[ $orderby ] ) ) {
					$meta_clause = $meta_clauses[ $orderby ];
					$parsed      = "CAST({$meta_clause['alias']}.meta_value AS {$meta_clause['cast']})";
				}
		}

		return $parsed;
	}

	/**
	 * Parses an 'order' query variable and cast it to 'ASC' or 'DESC' as necessary.
	 *
	 * @since 4.6.0
	 *
	 * @param string $order The 'order' query variable.
	 * @return string The sanitized 'order' query variable.
	 */
	protected function parse_order( $order ) {
		if ( ! is_string( $order ) || empty( $order ) ) {
			return 'ASC';
		}

		if ( 'ASC' === strtoupper( $order ) ) {
			return 'ASC';
		} else {
			return 'DESC';
		}
	}
}