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From: Dennis Lee Bieber <wlfraed@ix.netcom.com>
Newsgroups: comp.lang.python
Subject: Re: Howw to prevent the duplication of any value in a column within a CSV file (python)
Date: Tue, 26 Apr 2016 20:10:05 -0400
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On Tue, 26 Apr 2016 10:05:00 -0700 (PDT), Adam Davis
<peakgraphicz@gmail.com> declaimed the following:

>Here's my section of code:
>
>with open(class_code+".csv", 'a') as csvfile:
>        fieldnames = ["Name", "Score 1", "Score 2", "Score 3", "Average"]
>        writer = csv.DictWriter(csvfile, fieldnames=fieldnames)
>        #writer.writeheader()
>        writer.writerow({"Name": name, "Score 1": score1, "Score 2": score2, "Score 3": score3})
>
>It prints when requested as:
>
>Adam,1,0,0,0.3333333333333333
>Jake,9,10,6,8.333333333333334
>Tom,5,3,3,3.6666666666666665
>
>So basically, if anyone called Adam, Jake or Tom tries the quiz again, it will not let them.
>Thanks

	Probably not what you want, but...

	I'd drop the CSV file -- create an SQLite3 database with two tables:

TestTaker(*ID*, Name)

and

Scores(*ID*, _testTakerID_, TestID, Score)

where *ID* is the primary key -- autoincrement integer; _testTakeID_ is a
foreign key (the ID of the TestTaker); no need to store the average, you'll
compute that when retrieving data.

	If you set up (_testTakerID_, TestID) as a composite unique key, the
database system will object when you try to add a duplicate of those two
fields. 

	This design is not limited to only three scores (since TestID
identifies which score you can easily add more tests).

	You'd get the average by something like (this is off the cuff, I'd have
to test to get the syntax fully correct):

select TestTaker.Name, avg(Score) from 
TestTake inner join Scores
on TestTaker.ID = Scores.testTakerID
group by TestTaker.ID
order by TestTaker.Name


-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/