mysql - 如何解决sql中重复的id？

Question

SELECT DISTINCT `timeline_id` , `status_id`
FROM `timeline`,`status`
Where `timeline`.`user_id` = 1
ORDER BY `timeline`.`dates` DESC

输出为

timeline_id  status_id
1                1
1                2
1                3
2                1
2                2 
2                3
3                1
3                2
3                3

Answer 1

如果您在 tbl status 中有字段 user_id ，请尝试以下操作:

SELECT DISTINCT `timeline_id` , `status_id`
FROM `timeline` LEFT JOIN`status`
ON `timeline`.user_id = `status`.user_id
Where `timeline`.`user_id` = 1
ORDER BY `timeline`.`dates` DESC