[thelist] SQL In need of Optimization....

[Anthony Baratta]

Howdy...

I've got an interesting Query I need to perform on a Database and the route 
I've chosen most probably is the long way around to the answer. If someone 
has the time or inclination, any ideas would be appreciated:

__Background__

I have a table that holds information on what Majors a College is offering. 
Basically there are two fields: CollegeID & MajorID. I'm using this data as 
a "filter". Use selects what majors they want (Plus other criteria) and 
then they get a list of colleges that match their selections.

__Challenge__

My problem is that when someone selects more than one Major they would like 
to see offered. We want to select ALL colleges that offer both (or more) 
Majors. This is not the case of a simple use of AND.

If I use an AND:

SELECT ColumnOne, ColumnTwo, ColumnThree FROM tblCollegesSearch
WHERE
    tblCollegesSearch.CollegeID IN
    (SELECT distinct tblCollegeMajors.CollegeID
    FROM tblCollegeMajors WHERE
       tblCollegeMajors.MajorID = '1' AND
       tblCollegeMajors.MajorID = '2' AND
       tblCollegeMajors.MajorID = '3'
    )
GROUP BY ColumnOne, ColumnTwo, order by 1,2 desc

*or this way*

SELECT ColumnOne, ColumnTwo, ColumnThree FROM tblCollegesSearch
JOIN tblCollegeMajors
   ON (tblCollegeMajors.CollegeID = tblCollegesSearch.CollegeID)
WHERE
    tblCollegeMajors.MRMajorID = '1' AND
    tblCollegeMajors.MRMajorID = '2' AND
    tblCollegeMajors.MRMajorID = '3'
GROUP BY RegionID, AcceptanceRateCategory order by 1,2 desc


we get zero results. Which when you look at the way AND works, makes sense. 
So what we really need to do is create little groups of colleges that offer 
each major and select among those that belong to all groups. This is what I 
came up with:

SELECT ColumnOne, ColumnTwo, ColumnThree FROM tblCollegesSearch
WHERE
    tblCollegesSearch.CollegeID IN
    (select distinct tblCollegeMajors.CollegeID
    from tblCollegeMajors WHERE
       tblCollegeMajors.CollegeID IN
       (select tblCollegeMajors.CollegeID
        FROM tblCollegeMajors WHERE
           tblCollegeMajors.MajorID = '1')
       AND
       tblCollegeMajors.CollegeID IN
       (select tblCollegeMajors.CollegeID
        FROM tblCollegeMajors WHERE
           tblCollegeMajors.MajorID = '2')
       AND
       tblCollegeMajors.CollegeID IN
       (select tblCollegeMajors.CollegeID
        FROM tblCollegeMajors WHERE
           tblCollegeMajors.MajorID = '3')
    )
GROUP BY ColumnOne, ColumnTwo, order by 1,2 desc


Now this returns (I think) pretty good data!! Whee! ;-) But I can't help 
but wonder if there is a better way. Thoughts, ideas, and comments welcome.
---
Anthony Baratta
President
Keyboard Jockeys

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