I have three tables
Prospect -- holds prospect information
id
name
projectID
Sample data for Prospect
id | name | projectID
1 | p1 | 1
2 | p2 | 1
3 | p3 | 1
4 | p4 | 2
5 | p5 | 2
6 | p6 | 2
Conjoint -- holds conjoint information
id
title
projectID
Sample data
id | title | projectID
1 | color | 1
2 | size | 1
3 | qual | 1
4 | color | 2
5 | price | 2
6 | weight | 2
There is an associative table that holds the conjoint values for the prospects:
ConjointProspect
id
prospectID
conjointID
value
Sample Data
id | prospectID | conjointID | value
1 | 1 | 1 | 20
2 | 1 | 2 | 30
3 | 1 | 3 | 50
4 | 2 | 1 | 10
5 | 2 | 3 | 40
There are one or more prospects and one or more conjoints in their respective tables. A prospect may or may not have a value for each conjoint.
I'd like to have an SQL statement that will extract all conjoint values for each prospect of a given project, displaying NULL where there is no value for a value that is not present in the ConjointProspect table for a given conjoint and prospect.
Something along the lines of this for projectID = 1
prospectID | conjoint ID | value
1 | 1 | 20
1 | 2 | 30
1 | 3 | 50
2 | 1 | 10
2 | 2 | NULL
2 | 3 | 40
3 | 1 | NULL
3 | 2 | NULL
3 | 3 | NULL
I've tried using an inner join on the prospect and conjoint tables and then a left join on the ConjointProspect, but somewhere I'm getting a cartesian products for prospect/conjoint pairs that don't make any sense (to me)
SELECT p.id, p.name, c.id, c.title, cp.value
FROM prospect p
INNER JOIN conjoint c ON p.projectID = c.projectid
LEFT JOIN conjointProspect cp ON cp.prospectID = p.id
WHERE p.projectID = 2
ORDER BY p.id, c.id
prospectID | conjoint ID | value
1 | 1 | 20
1 | 2 | 30
1 | 3 | 50
1 | 1 | 20
1 | 2 | 30
1 | 3 | 50
1 | 1 | 20
1 | 2 | 30
1 | 3 | 50
2 | 1 | 10
2 | 2 | 40
2 | 1 | 10
2 | 2 | 40
2 | 1 | 10
2 | 2 | 40
3 | 1 | NULL
3 | 2 | NULL
3 | 3 | NULL
Guidance is very much appreciated!!