
如何列出MySQL数据库(分步代码教程)
count_users ( $strategy = 'time', $site_id = null )
WordPress中的count_users函数用来计算WordPress网站上的用户数量: 这个函数返回一个数组,包含每个用户角色的用户数量。
计算拥有每个用户角色的用户数量。
假设既不存在重复的也不存在孤儿的权限元值。
假设角色名称是唯一的短语。与WP_User_Query::prepare_query()的假设相同。
使用$strategy = ‘time’ 这是CPU密集型的,应该可以处理大约10^7个用户。
使用$strategy = ‘memory’,这是内存密集型的,应该可以处理大约10^5个用户,但请看WP Bug #12257。
function count_users( $strategy = 'time', $site_id = null ) { global $wpdb; // Initialize. if ( ! $site_id ) { $site_id = get_current_blog_id(); } /** * Filters the user count before queries are run. * * Return a non-null value to cause count_users() to return early. * * @since 5.1.0 * * @param null|array $result The value to return instead. Default null to continue with the query. * @param string $strategy Optional. The computational strategy to use when counting the users. * Accepts either 'time' or 'memory'. Default 'time'. * @param int $site_id The site ID to count users for. */ $pre = apply_filters( 'pre_count_users', null, $strategy, $site_id ); if ( null !== $pre ) { return $pre; } $blog_prefix = $wpdb->get_blog_prefix( $site_id ); $result = array(); if ( 'time' === $strategy ) { if ( is_multisite() && get_current_blog_id() != $site_id ) { switch_to_blog( $site_id ); $avail_roles = wp_roles()->get_names(); restore_current_blog(); } else { $avail_roles = wp_roles()->get_names(); } // Build a CPU-intensive query that will return concise information. $select_count = array(); foreach ( $avail_roles as $this_role => $name ) { $select_count[] = $wpdb->prepare( 'COUNT(NULLIF(`meta_value` LIKE %s, false))', '%' . $wpdb->esc_like( '"' . $this_role . '"' ) . '%' ); } $select_count[] = "COUNT(NULLIF(`meta_value` = 'a:0:{}', false))"; $select_count = implode( ', ', $select_count ); // Add the meta_value index to the selection list, then run the query. $row = $wpdb->get_row( " SELECT {$select_count}, COUNT(*) FROM {$wpdb->usermeta} INNER JOIN {$wpdb->users} ON user_id = ID WHERE meta_key = '{$blog_prefix}capabilities' ", ARRAY_N ); // Run the previous loop again to associate results with role names. $col = 0; $role_counts = array(); foreach ( $avail_roles as $this_role => $name ) { $count = (int) $row[ $col++ ]; if ( $count > 0 ) { $role_counts[ $this_role ] = $count; } } $role_counts['none'] = (int) $row[ $col++ ]; // Get the meta_value index from the end of the result set. $total_users = (int) $row[ $col ]; $result['total_users'] = $total_users; $result['avail_roles'] =& $role_counts; } else { $avail_roles = array( 'none' => 0, ); $users_of_blog = $wpdb->get_col( " SELECT meta_value FROM {$wpdb->usermeta} INNER JOIN {$wpdb->users} ON user_id = ID WHERE meta_key = '{$blog_prefix}capabilities' " ); foreach ( $users_of_blog as $caps_meta ) { $b_roles = maybe_unserialize( $caps_meta ); if ( ! is_array( $b_roles ) ) { continue; } if ( empty( $b_roles ) ) { $avail_roles['none']++; } foreach ( $b_roles as $b_role => $val ) { if ( isset( $avail_roles[ $b_role ] ) ) { $avail_roles[ $b_role ]++; } else { $avail_roles[ $b_role ] = 1; } } } $result['total_users'] = count( $users_of_blog ); $result['avail_roles'] =& $avail_roles; } return $result; }