SQL query issue in Django

Question

I am trying to find out if a value is present in a column in a MySQL table from my django application. This is what I have done:

cursor = connection.cursor()
cursor.execute('SELECT COUNT(*) FROM model_combination_bank WHERE combination = %s AND validity = 1', [combination])
result = cursor.fetchall
if result != 1:
    self.respond('Sorry. The entry code you entered is not valid. Please try again with a valid code.')
    return()

I know for sure that there is a 1 row in the table that matches the SELECT STATEMENT but the self.respond function runs. Can somebody kindly tell me whats wrong with my code.

Daniel Roseman · Accepted Answer · 2015-01-30 20:46:14Z

1

You didn't call the method:

result = cursor.fetchall()

However you shouldn't really be using raw SQL here. Use the model layer:

result = ModelCombinationBank.objects.filter(validity=1, combination=combination).count()

assuming your model is called ModelCombinationBank. And if all you need to is to check that the combination exists, use exists() instead of count(), since that is a cheaper query.

edited Jan 30, 2015 at 20:46

answered Jan 30, 2015 at 20:39

Daniel Roseman

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warath-coder · Accepted Answer · 2015-01-30 20:44:04Z

0

Another way to see if a value exists and do something if it does:

try:
    obj = ModelCombinationBank.objects.get(validity=1, combination=combination)
    # do something with obj
except ModelCombinationBank.DoesNotExist:
    # do something if not found

answered Jan 30, 2015 at 20:44

warath-coder

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