check if sqlite3 python data exists

Question

This is my code :

import sqlite3

def delete_product(data):
    with sqlite3.connect("main.db") as db:
        cursor = db.cursor()
        sql = "delete from Products where Name=?"
        if cursor.rowcount <= 0:
            print("The product {0} does not exist" .format(name))
        if cursor.rowcount > 0:
            cursor.execute(sql,data)
            db.commit()
            print("The product {0} has been delted successfully" .format(name))

if __name__ == "__main__":
    name=input("Enter the name of the product you want to delete: >>")
    data=(name,)
    delete_product(data)

I want to check if the name actually exists in the database or not if it exists then delete it. if it doen't exist then print out an error. can anyone help me spot where the problem is

You should post full error message. It will help identify the problem. — beeftendon
– beeftendon, Commented Dec 21, 2016 at 21:44
You should probably specify what output do you get and why it is unexpected. — Yevhen Kuzmovych
– Yevhen Kuzmovych, Commented Dec 21, 2016 at 21:45
@beeftendon there is no error message it's just the checking if exists bit doesn't work — Saqib Malik
– Saqib Malik, Commented Dec 21, 2016 at 21:45
@YevhenKuzmovych there is no output it just tells me the product doesnt exist even though it does — Saqib Malik
– Saqib Malik, Commented Dec 21, 2016 at 21:47
There is no need for any of this. Just execute "delete from Products where Name=?". If it exists, it's deleted. If it doesn't, nothing is deleted. — roganjosh
– roganjosh, Commented Dec 21, 2016 at 21:58

beeftendon · Accepted Answer · 2016-12-21 21:56:37Z

1

Regarding cursors, the Python sqlite3 documentation states:

As required by the Python DB API Spec, the rowcount attribute “is -1 in case no executeXX() has been performed on the cursor...

You define the cursor variable without performing any execute command. Thus, cursor.rowcount will be -1, and cursor.rowcount <= 0 will always be true.

Maybe you intended to place the line

cursor.execute(sql,data)

before the first cursor.rowcount check?

answered Dec 21, 2016 at 21:56

beeftendon

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