多个表中的SQL计数超过1个值_Sql_Postgresql

多个表中的SQL计数超过1个值

sql postgresql

多个表中的SQL计数超过1个值,sql,postgresql,Sql,Postgresql,我有一个类似以下内容的DB模式： CREATE TABLE projects (project_id int); CREATE TABLE project_members (user_id int, project_id int); CREATE TABLE project_issues (issue_id int, project_id int); 我想要的是找到所有有10个或更多成员以及10个或更多问题的项目。我很难对此提出质疑我希望输出类似于： project_id | members

我有一个类似以下内容的DB模式：

CREATE TABLE projects (project_id int);
CREATE TABLE project_members (user_id int, project_id int);
CREATE TABLE project_issues (issue_id int, project_id int);

我想要的是找到所有有10个或更多成员以及10个或更多问题的项目。我很难对此提出质疑

我希望输出类似于：

project_id | members | issues
-----------+---------+-------
65         | 100     | 23
93         | 78      | 45

最好按成员排序，然后按问题排序

我提出了：

SELECT projects.project_id, COUNT(project_members.user_id) FROM 
project_members LEFT JOIN projects ON 
project_members.project_id = projects.project_id GROUP BY projects
ORDER BY count;

但我也不知道如何把它带到下一个计算问题的层面

我正在使用PostgreSQL 9.1

这可能会更有效，但它给出了正确的结果

SELECT 
  p.project_id,
  m.members,
  i.issues
FROM projects AS p
LEFT JOIN 
  (
      SELECT project_id, COUNT(user_id) AS members 
      FROM project_members 
      GROUP BY project_id
  ) AS m
ON p.project_id = m.project_id
LEFT JOIN 
  (
      SELECT project_id, COUNT(issue_id) AS issues 
      FROM project_issues
      GROUP BY project_id
  ) AS i
ON p.project_id = i.project_id
WHERE members > 10 AND issues > 10
ORDER BY members, issues;

这可能会更有效，但它给出了正确的结果

SELECT 
  p.project_id,
  m.members,
  i.issues
FROM projects AS p
LEFT JOIN 
  (
      SELECT project_id, COUNT(user_id) AS members 
      FROM project_members 
      GROUP BY project_id
  ) AS m
ON p.project_id = m.project_id
LEFT JOIN 
  (
      SELECT project_id, COUNT(issue_id) AS issues 
      FROM project_issues
      GROUP BY project_id
  ) AS i
ON p.project_id = i.project_id
WHERE members > 10 AND issues > 10
ORDER BY members, issues;

更简单、更快一点：

SELECT p.project_id, m.members, i.issues
FROM   projects p
JOIN  (
    SELECT project_id, count(*) AS members 
    FROM   project_members 
    GROUP  BY project_id
    HAVING count(*) >= 10
    ) m USING (project_id)
JOIN  (
    SELECT project_id, COUNT(*) AS issues 
    FROM   project_issues
    GROUP  BY project_id
    HAVING count(*) >= 10
    ) i  USING (project_id)
ORDER  BY m.members DESC, i.issues DESC;

既然你想要项目

有10个或更多成员以及10个或更多问题的

。。您可以通过

JOIN

和

have

尽早淘汰不符合条件的候选人，以获得更快的结果。
再加上一些其他的小调整

将

=10

或

>9

表示“10或更多”

警惕“代理交叉连接”：