Question

I have the following SQL for my PHP project, I need to receive the Module Status Text to match the status Id in the Module Table, but if the status id value doesn’t exist, can I set a value in the SQL?
This is a simple Query but Im looking for an efficient solution so I dont have to run 2 seperate queries.

Thanks in advance..

Below is what I have now but it does select the values that are not reference in ModuleStatus.

SELECT m.moduleID, m.moduleDesc,s.statusDesc,
FROM Modules m, ModuleStatus s 
WHERE s.statusID = m.statusID

Below is a simplified version of the results Im getting…

Module

+--------+---------+---------+
|   ID   |   Desc  |  Stat   |
+--------+---------+---------+
|   5    |   Car   |  1      |
+--------+---------+---------+
|   6    |   Bike  |  2      |
+--------+---------+---------+

ModuleStatus

+--------+---------+
|   ID   |   Desc  |
+--------+---------+
|   1    | on      |
+--------+---------+
|   0    | off     |
+--------+---------+

The results would be

Result

+--------+---------+---------+
|   ID   |   Desc  |  Stat   |
+--------+---------+---------+
|   5    |   Car   |  on     |
+--------+---------+---------+

But What I want is

Expect!!

+--------+---------+---------+
|   ID   |   Desc  |  Stat   |
+--------+---------+---------+
|   5    |   Car   |  on     |
+--------+---------+---------+
|   6    |   Bike  | Unknown |
+--------+---------+---------+

Answer 1

You need a left outer join :

SELECT m.moduleID, m.moduleDesc,s.statusDesc,
FROM Modules m
LEFT OUTER JOIN ModuleStatus s 
ON s.statusID = m.statusID

Good examples in this answer -> What is the difference between "INNER JOIN" and "OUTER JOIN"?

As suggested by @MGA … you could change the missing values to “unknown” by updating the select statement :

SELECT m.moduleID, m.moduleDesc, IsNull(s.statusDesc,'Unknown')
FROM Modules m
LEFT OUTER JOIN ModuleStatus s 
ON s.statusID = m.statusID