Comparing SQL results with Python

Question

I was looking for a way to my program to take 2 values from my database, compare them and update or insert some value. I tried in sqlite3 but I didn't find a good solution and I tried on python, but when I run the program, the values are different and never match. I already look on google, here on stack overflow, but didn't find anything.

cursor.execute("select * from [Sistema]")
Teste = cursor.fetchall()
cursor.execute("select [SistemaOperacional] from [Sistema] where [SistemaOperacional] = 'teste'")
comparacao = cursor.fetchall()
testando = comparacao
for row in Teste:
    #I was checking the values to see if they where equal
    print(comparação[0]) #Value ('teste',)
    print(row[0]) #Value 'teste'
    if row[0] == comparação[0]:
        cursor.execute("Update [Sistema] set [SistemaOperacional] = '1' where [VersaoBanco] = 3")
        print('Executado')
        break
    else:
        cursor.execute("insert into [Sistema] values ('9','9','1')")
        print('não')
        break

the output whas

('teste',)
teste
não

I wasn't finding a solution for this in sql, that's why I tried with python, but I'm open to listen any other suggestion than python

Please give us an example of a short input, what output you get, and what output you expect. — David Collins
– David Collins, Commented Sep 7, 2020 at 3:58

alice c · Accepted Answer · 2020-09-06 16:30:32Z

2

It's a pretty common problem for people unfamiliar with Python/MySQL to run into troubles receiving tuples back from querying. comparacao[0] is a tuple. Tuples are compared lexicographically by element, so you'd have to retrieve the first element (like @Gwyn Evans said) e.g. comparação[0][0] in order to compare it to your string row.

Here is a link to Python docs about comparisons: https://docs.python.org/2.0/ref/comparisons.html

answered Sep 6, 2020 at 16:30

alice c

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2 Comments

Kaue Gomes Over a year ago

Thanks, this doc is helping me a lot, I was thinking about other situations, this will clarify a lot :)

alice c Over a year ago

no problem!!! always glad to help :) python is truly awesome

Gwyn Evans · Accepted Answer · 2020-09-06 16:23:10Z

1

I could be on the wrong track here, but isn't your comparação[0] itself a tuple, so you probably want to be comparing comparação[0][0] with row[0].

answered Sep 6, 2020 at 16:23

Gwyn Evans

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