sqlite3 Select语句在Python中不起作用

Question

I have an sqlite3 database which has been created via the following CREATE statement in a .sql file:

create.sql

CREATE TABLE dogs (id INTEGER PRIMARY KEY, 
                   name TEXT, 
                   age INTEGER, 
                   gender CHAR(1), 
                   breed TEXT, 
                   temperament TEXT, 
                   hungry BOOLEAN);

And seeded with the following data via an INSERT statement in a .sql file:

insert.sql

INSERT INTO dogs (name, age, gender, breed, temperament, hungry) VALUES
                 ("Snoopy", 3, "M", "beagle", "friendly", 1),
                 ("McGruff", 10, "M", "bloodhound", "aware", 0),
                 ("Scooby", 6, "M", "great dane", "hungry", 1),
                 ("Little Ann", 5, "F", "coonhound", "loyal", 0),
                 ("Pickles", 13, "F", "black lab", "mischievous", 1),
                 ("Clifford", 4, "M", "big red", "smiley", 1),
                 ("Lassie", 7, "F", "collie", "loving", 1),
                 ("Snowy", 8, "F", "fox terrier", "adventurous", 0),
                 (NULL, 4, "M", "golden retriever", "playful", 1);

I have a Python Jupyter notebook where I am performing the following actions to create and populate the database 'pets.db':

import sqlite3
connection = sqlite3.connect('pets.db')

cursor = connection.cursor()

file = open("./create.sql", 'r')
create_sql = file.read()
cursor.executescript(create_sql)

file1 = open("./insert.sql", 'r')
insert_sql = file1.read()
cursor.executescript(insert_sql)

Then I have a file of Python functions titled 'selects.py' where I am storing SQL select statements. The first one, shown below, is meant to return the name and breed of all female dogs in the table.

def sql():
    return "SELECT name, breed FROM dogs WHERE gender = 'F';"

I then try to run the above function in Jupyter:

from selects import sql
cursor.execute(sql()).fetchall()

And I receive the following error:

NameError: name 'f' is not defined

I've been trying for the past hour to format the select statement in a way which works in the Python file, but am coming up short each time. Is it the way that the SQL SELECT statement is written that is incorrect or is it something in the format of the Python code?

edit: Here is the complete traceback:

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-87-df843ecc4fb9> in <module>()
      1 from selects import sql
----> 2 cursor.execute(sql())
      3 results = cursor.fetchall()
      4 results

~/ds-practice/selects.py in sql()
      1 def sql():
----> 2     return "SELECT name, breed FROM dogs WHERE gender = 'F';"
      3 
      4 
      5 

NameError: name 'f' is not defined

Answer 1

It looks like your question is missing some key information. The error NameError: name 'f' is not defined is a Python error, indicating that you're referring to something supposedly called f , which has not been defined yet.

Executing the SQL you provided and running the below script from Python works without problems:

import sqlite3

connection = sqlite3.connect('pets.db')
cursor = connection.cursor()


def sql():
    return "SELECT name, breed FROM dogs WHERE gender = 'F';"


cursor.execute(sql()).fetchall()

With the error, you probably also receive a line number and module name where this error occurs. You should probably look closely at how the exact spelling differs from the above.