根据app_id来分组统计数量 CREATE TABLE aiops_cost ( `app_id` varchar(100) COLLATE utf8mb4_unicode_ci NOT NULL, `app_name` varchar(100) COLLATE utf8mb4_unicode_ci DEFAULT NULL, `costCenter` varchar(100) COLLATE utf8mb4_unicode_ci DEFAULT NULL, `serviceType` varchar(100) COLLATE utf8mb4_unicode_ci DEFAULT NULL, `product` varchar(100) COLLATE utf8mb4_unicode_ci DEFAULT NULL, `productCatalog` varchar(100) COLLATE utf8mb4_unicode_ci DEFAULT NULL, `id` bigint NOT NULL AUTO_INCREMENT )

You can use the following query to get the count of app_id for each month:
SELECT
    MONTH(created_at) AS month,
    COUNT(*) AS count
FROM
    app
GROUP BY
    MONTH(created_at)
ORDER BY
    MONTH(created_at);