mysql - 如何使用 MySQL OUTER JOIN 单独分组的表

Question

我有两个单独的表，我需要根据分组的日期列加入它们（原始值有特定的日期，我需要它们按月），我似乎找不到这样做的方法，因为我将它们分组为不同的特征。表格如下：

第一的：

SELECT  DATE_FORMAT(`Samples`.`created_at`,'%Y-%m') AS `Month of Created At`
        COUNT(DISTINCT `Samples`.`id`) AS `Samples X`
FROM `samples` AS `Samples`
WHERE `Samples`.`group` = 'x'
       AND `Samples`.`created_at` BETWEEN DATE_SUB(CURRENT_TIMESTAMP, INTERVAL 3 YEAR) AND CURRENT_TIMESTAMP
ORDER BY `Month of Created At` ASC

输出样本：

Month of Created At   Samples X
            2020-01          54
            2020-02         224
            2020-03         467
            2020-04         453
            2020-05         354

第二：

SELECT  DATE_FORMAT(`Samples`.`created_at`,'%Y-%m') AS `Month of Created At`
        COUNT(DISTINCT `Samples`.`id`) AS `Samples Y`
FROM `samples` AS `Samples`
WHERE `Samples`.`section` = 'y'
       AND `Samples`.`created_at` BETWEEN DATE_SUB(CURRENT_TIMESTAMP, INTERVAL 3 YEAR) AND CURRENT_TIMESTAMP
ORDER BY `Month of Created At` ASC

输出样本：

Month of Created At   Samples Y
            2020-02           2
            2020-05           7

我需要最终结果是这样的：

Month of Created At   Samples X   Samples Y
            2020-01          54
            2020-02         224           2
            2020-03         467
            2020-04         453
            2020-05         354           7

标签： mysql