Question

I am not very good with SQL so I will post the tables I am working with and what I have tried.

Table 1

Installation
   id

Table 2 links to 1

Project
   id
   installationid
   name

Table 3 links to 2

Assignment
   id
   projectid

Table 4 links to 3

AssignmentException
   id
   assignmentid
   type

I am trying to find Project.name where AssignmentException.type > 0 for Installation.id = 12345. The most experience I have is with simple inner joins. The following is my nonworking attempt that fails to take into account Installationid. A short explanation of how your code works would also be greatly appreciated.

select * from ( 
    Assignment INNER JOIN AssignmentException ON Assignment.id = AssignmentException.assignmentID )
    INNER JOIN Project ON Assignment.projectid = Project.id
    WHERE AssignmentException.type > 0

Answer 1

How about this:

SELECT p.name
FROM AssignmentException ex
    JOIN Assignment a ON ex.id = a.AssignmentId
    JOIN Project p ON a.ProjectId = p.Id
WHERE ex.type > 0
    AND p.InstallationId = 12345