PHP MySQL Join users table to multiple columns and rows
I'm having some problems with tables in a project I am working on for projects.
I have 3 tables, one for projects, one for clients and one for users. I am trying to store the client and user id in the Projects table and join them on checkout.
+----+--------------+
| ID | CustomerName |
+----+--------------+
| 1 | Customer 1 |
| 2 | Customer 2 |
| 3 | Customer 3 |
+----+--------------+
+----+-----------+----------+
| ID | FirstName | LastName |
+----+-----------+----------+
| 1 | Bob | Belcher |
| 2 | Stirling | Archer |
| 3 | Bart | Simpson |
| 4 | Peter | Griffin |
| 5 | BoJack | Horseman |
| 6 | Eric | Cartman |
+----+-----------+----------+
+----+---------------+-----------------+-------------+-------------------+-------------------+--------------------+
| ID | ProjectNumber | ProjectCustomer | ProjectLead | ProjectElectrical | ProjectMechanical | ProjectDescription |
+----+---------------+-----------------+-------------+-------------------+-------------------+--------------------+
| 1 | 0001 | 1 | 3 | 4 | 6 | Project 1 |
| 2 | 0002 | 2 | 2 | 5 | 5 | Project 2 |
| 3 | 0003 | 3 | 1 | 6 | 4 | Project 3 |
+----+---------------+-----------------+-------------+-------------------+-------------------+--------------------+
I've been playing with Select all day and this is as far as I could find SO:
select Projects.ProjectNumber, Customers.CustomerName, CONCAT_WS(' ', Users.FirstName, Users.LastName) AS ProjectLead, Projects.ProjectElectrical, Projects.ProjectMechanical, Projects.ProjectDescription FROM Projects
INNER JOIN Customers ON Projects.ProjectCustomer = Customers.ID
LEFT JOIN Users ON Projects.ProjectLead = Users.ID
Which helps me with this:
+---------------+--------------+-----------------+-------------------+-------------------+--------------------+
| ProjectNumber | CustomerName | ProjectLead | ProjectElectrical | ProjectMechanical | ProjectDescription |
+---------------+--------------+-----------------+-------------------+-------------------+--------------------+
| 0001 | Customer 1 | Bart Simpson | 4 | 6 | Project 1 |
| 0002 | Customer 2 | Stirling Archer | 5 | 5 | Project 2 |
| 0003 | Customer 3 | Bob Belcher | 6 | 4 | Project 3 |
+---------------+--------------+-----------------+-------------------+-------------------+--------------------+
But for my life, I can't get ProjectElectrical and ProjectMechanical to do the same as ProjectLead. I either get duplicate ProjectLead or I get NULL.
Can anyone help point me in the right direction? Do I need to completely redesign my query or am I on the right track?
I have scripted it on SQL Fiddle
Thanks in advance for any answers!
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1 answer
Here is the updated script request:
select Projects.ProjectNumber, Customers.CustomerName, CONCAT_WS(' ', Users.FirstName, Users.LastName) AS ProjectLead, CONCAT_WS(' ', u2.FirstName, u2.LastName) AS ProjectElectrical, CONCAT_WS(' ', u3.FirstName, u3.LastName) AS ProjectMechanical, Projects.ProjectDescription FROM Projects
INNER JOIN Customers ON Projects.ProjectCustomer = Customers.ID
LEFT JOIN Users ON Projects.ProjectLead = Users.ID
LEFT JOIN Users AS u2 ON Projects.ProjectElectrical = u2.ID
LEFT JOIN Users AS u3 ON Projects.ProjectMechanical = u3.ID
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