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sql query

marys joseph

Joined: May 14, 2004
Posts: 20

I need help for a sql query, i have 2 tables.

table a: studentid sname
table b: studentid, studentNumber.

sometimes same studentid has 1 or more studentnumbers.

I need to display studentid,studentnumber,sname

when I join I always get multiple rows of same student because the student has more than 1 student number. I want to get only one studentnumber if the student has more. how can i do that. I used distinct keyword but the rows are not actually different.

Jeff Pavlocak

Joined: Apr 26, 2004
Posts: 16
Try the following:

SELECT table_a.studentid, MAX(studentnumber), sname
FROM table_a, table_b
WHERE table_a.studentid = table_b.studentid
GROUP BY studentid, sname;
Julian Kennedy
Ranch Hand

Joined: Aug 02, 2004
Posts: 823
Hi Marys,

Did Jeff's suggestion work? I would expect it to produce the same results as DISTINCT.

When you want to remove duplicates from a result set where the rows are identical you tend to have to resort to database pseudo-columns such as Oracle's rowid.

If you're still having trouble you might want to check that out.

Jeanne Boyarsky
author & internet detective

Joined: May 26, 2003
Posts: 32815

I would expect Jeff's example to work and produce different results than distinct. Since the student number is different, the rows aren't exactly the same and distinct wouldn't be able to filter them out.

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