mysql - 选择 COUNT 与三个表 - mysql

Question

我正在尝试通过一个查询(使用 WHERE 条件)选择包含三个表的 COUNT。

这是我的代码，无法正常工作。

SELECT t1.count(id) AS car_model_count,t2.count(id) AS list_item_count,t3.count(id) 
    FROM `car_model` AS t1
    INNER JOIN `list_item` AS t2
    INNER JOIN `part_item` AS t3
    WHERE t1.user_id=3;

Answer 1

可以通过使用子查询或UNION可以从多个表中获取COUNT。尝试这个查询:

SELECT 
    (SELECT count(*) FROM `car_model` WHERE user_id=3 ) AS car_model_count,
    (SELECT COUNT(*) FROM `list_item` WHERE user_id=3) AS list_item_count,
    (SELECT count(*) FROM `part_item` WHERE user_id=3) AS part_item_count;