相关疑难解决方法(0)

除了MYSQL中的行数据之外,获得行级别的最佳方法是什么？

例如,假设我有一份学生名单,我想在GPA中排名.我知道我可以通过GPA订购,但是有什么最快的方式让MYSQL在我回来的rowdata中返回等级？

SQL(MySQL)中是否有办法在特定字段上执行"循环"ORDER BY？

举个例子,我想拿一个像这样的表:

+-------+------+
| group | name |
+-------+------+
|     1 | A    |
|     1 | B    |
|     1 | C    |
|     2 | D    |
|     2 | E    |
|     2 | F    |
|     3 | G    |
|     3 | H    |
|     3 | I    |
+-------+------+

并运行以此顺序生成结果的查询:

+-------+------+
| group | name |
+-------+------+
|     1 | A    |
|     2 | D    |
|     3 | G    |
| …

SELECT DISTINCT users.id as expert_id, users.firstname, users.lastname
    , projects.id as project_id, projects.project_title
    , projects.project_budget, projects.created as project_created
FROM USERS
RIGHT JOIN expert_skills ON expert_skills.expert_id = users.id
JOIN project_skills ON project_skills.skill_id = expert_skills.skill_id
JOIN projects ON projects.id = project_skills.project_id
WHERE projects.status = 1

此查询为我提供了与用户相关的不同项目,但我想限制每位专家的项目数.例如,我想要与专家相关的项目,但项目数量最多可达10个.我的查询需要一个限制工具.我怎么能这样做？谢谢