无法访问元组的索引。 IndexError：列表索引超出范围

Question

I created a db with sqlite3 in python, I then added a table with 5 parameters. I added an entry to the table filling all 5 parameters. I'm trying to select all entries with a specific parameter 'user'.

If I print the selected tuple without an index, it returns a tuple with 5 parameters as expected .

If I print the tuple with an index of [0], it return a tuple with 5 parameters instead of the first parameter only.

If I print the entry with an index of higher than [0], for example [1], it returns IndexError: list index out of range.

I would like to access all of the indexes, but I don't know how to do it other than how I tried.

Code below: (financedb is my other .py file that contains a function db_connect() connecting to the database. I included that function in the code below so that the code is easier to replicate.)

import sqlite3
import financedb as fdb

user_name_input = input('Username: ')


def check_the_balance():

    fdb.db_connect() # Establishes connection to DB

    fdb.cursor.execute('SELECT * FROM test WHERE user=?', [user_name_input])
    check = fdb.cursor.fetchall()
    print(check[0])

def db_connect():

    global connection 
    global cursor 

    cursor = connection.cursor()
    command = f'CREATE TABLE test(id integer, user text, password text, montly_income real, monthly_debt real)'

    try:
        cursor.execute(command)

    except sqlite3.OperationalError:
        pass

    finally:
        connection.commit()
check_the_balance()  

Answer 1

.fetchall returns a list of rows, so I would assume that you want check[0][0] ? This may give you what you want:

def check_the_balance():

    fdb.db_connect() # Establishes connection to DB

    fdb.cursor.execute('SELECT * FROM test WHERE user=?', [user_name_input])
    for items in fdb.cursor.fetchall():
        print(items)
        print(items[0])

Answer 2

I believe fetchall will return a list of rows, so check[0] represents the first row, of which the first element is the one you are looking for. It may also return an empty list though, I would check if its length is positive before accessing the first value