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T-SQL Query for Top 1 for each date

Posted on 2012-03-13
2
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Last Modified: 2012-08-13
Hello Experts,

I have a table called [Exam_Results], and it has to following colums:
[ID] int
[UserID] int
[ExamID] int
[Score] float
[Date] datetime

Users can take exams multiple times and the data looks as follows:

ID     UserID     ExamID     Score      Date
----------------------------------------------------------------------------
1          20            1               75          2012-02-15 13:30:00
2          20            1               83          2012-02-17 10:30:00
3          20            2               80          2012-02-15 13:30:00
4          54            3               64          2012-02-16 13:30:00
5          54            3               78          2012-02-20 14:30:00

What I am trying to get is the first time each user took the exam, so I want my select to return the top 1 result for each user.

So with the data above, my query would return:
UserID     ExamID     Score
-------------------------------------------
20                1              75
20                2              80
54                3              64

So, I need help to write a select query that for each User and Exam ID, will return the score from the first time the exam was completed by each user.
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Question by:NursingCorp
2 Comments
 
LVL 8

Accepted Solution

by:
fundacionrts earned 500 total points
ID: 37717576
SELECT ER1.UserID, ER1.ExamID, ER1.Score
FROM Exam_Results AS ER1
WHERE ER1.Date <= (
SELECT MIN( ER2.Date )
FROM Exam_Results AS ER2
WHERE ER2.UserID = ER1.UserID
AND ER2.ExamID = ER1.ExamID )
0
 

Author Closing Comment

by:NursingCorp
ID: 37717665
Worked Perfectly - Thanks for the clear, quick solution!
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