SQL-查询字符串请求

Question

Photos.Pr_ID is foreign key for Projects.Pr_ID

I need Project.Name, Project.Pro_ID, COUNT Photo.PID for each Photo.Pr_ID and TOP 1 Photos.P_Path for that project. I'm giving User_Id as a condition parameter to query. The result should be GROUP BY Projects.Pro_ID as well.

Answer 1

SELECT Project.Name, Project.Pro_ID, sub.P_Path, COUNT(Photo.PID)
FROM Project
JOIN Photo ON Project.Pro_ID = Photo.Pro_ID
JOIN (SELECT P_Path FROM Projects GROUP BY Pro_ID, P_Path) sub
ON sub.Pro_ID = Project.Pro_ID
GROUP BY Projects.Pro_ID, Project.Name, sub.P_Path

This should get you at least relatively close to the results you are looking for. This assumes the P_Path value is duplicated for all Projects. I prefer not to do a SELECT TOP 1 in a subquery wherever possible.

Answer 2

@Jacob HI made necessary changes.

SELECT Projects.Name, Projects.Pro_ID, sub.P_Path, COUNT(Photos.PID)
FROM Projects
JOIN Photos ON Projects.Pro_ID = Photos.Pr_ID
JOIN (SELECT Pr_ID,P_Path FROM Photos GROUP BY Pr_ID, P_Path) sub
ON sub.Pr_ID = Projects.Pro_ID
GROUP BY Projects.Pro_ID, Projects.Name, sub.P_Path

But result shows me recurrent Projects.Pro_ID. Lastly I just need to get a Project ID once.