'NoneType' object is not subscriptable in Python and SQLite

Question

There is problem with my code:

    if db_connection:
        cur_bal = db_connection.                                 \
            cursor().                                            \
            execute(f"""
                    select x from A
                      where x > {bound * 2};
                    """).                                        \
            fetchone()[0]

Python is writing: 'NoneType' object is not subscriptable. What's wrong with this?

I think that problem with fetchone()[0] but I don't know exactly

It means there's no record in your database that matched the query. — deceze, Aug 04 '23 at 09:16

score 1 · Answer 1 · answered Aug 04 '23 at 09:16

The error "'NoneType' object is not subscriptable" occurs when attempting to access an element of a variable that is None. In the provided code, the issue arises from the use of fetchone()[0], where fetchone() returns None.

This situation usually happens when the query does not return any results from the database, causing fetchone() to return None. To resolve this error and handle the case when no results are returned, we need to implement a check for None before accessing the elements.

Try this:

if db_connection:
    cursor = db_connection.cursor()
    cursor.execute(f"""
                    SELECT x FROM A
                    WHERE x > {bound * 2};
                    """)
    result = cursor.fetchone()

    if result is not None:
        cur_bal = result[0]
    else:
        # Handle the case when there are no matching records
        cur_bal = None  # or any other default value you want to assign

Thanks. The problem was in result of script: it returned None — Maximilian Horten, Aug 04 '23 at 12:37

'NoneType' object is not subscriptable in Python and SQLite

1 Answers1