using sqlite with python, fetchall()

Question

I am trying to compare a list of links to the liks stored in an sqlite database.

assuming the links in the database are:

link.com\page1

link.com\page2

link.com\page3

I have written the following code to chick if a given link exists in the database and adds it if it did not exist.

links = ['link.com\page2', 'link.com\page4']
c.execute('SELECT link FROM ads')
previouslinks = c.fetchall()

for l in links:
    if l not in previouslinks:
        c.execute('''INSERT INTO ads(link) VALUES(?)''', (l))
        conn.commit()
    else:
        pass

the problem is even though the link is in the database, the script does not recognise it!

when I try to print previouslinks variable, results look something like this:

[('link.com\page1',), ('link.com\page2',), ('link.com\page3',)]

I think the problem is with the extra parentheses and commas, but I am not exactly sure.

CL. · Accepted Answer · 2017-12-09 08:16:38Z

1

fetchall() returns a list of rows, where each row is a tuple containing all column values. A tuple containing a string is not the same as the string.

You have to extract the values from the rows (and you don't need fetchall() when iterating over a cursor):

previouslinks = [row[0] for row in c]

answered Dec 9, 2017 at 8:16

CL.

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