I would like some advice why this would not insert data into my SQL table

问题

Following is my code:

import MySQLdb
def insert_popularity(PersonNumber, Category, Value):

# make a connection to the dataabse
connection = MySQLdb.connect(host='localhost', user='root', \
                             passwd='password', db='inb104')

# get a cursor on the database
cursor = connection.cursor()

# construct the SQL statement
sql = ("""INSERT INTO popularity (PersonNumber, Category, Value)
        VALUES(%s, %s, %s)""", (number, category, data))

def open_file(filename):        
    txt_file = file(filename, 'r')
    for line in txt_file:
        # Split the line on whitespace
        for value in line.split():                
            return value

            number = value[0]
            data = value[1]

# execute the query
cursor.execute(sql)

# commit the changes to the database\
connection.commit()

# close the cursor and connection
cursor.close()

connection.close()

Update:

After changing my code as per Paulo's suggestion I now get this error:

query() argument 1 must be string or read-only buffer, not tuple. 

I am not sure what it is after trying to change my code:

def insert_popularity(Category, filename, cursor):

    txt_file = file(filename, 'r')
    for line in txt_file:
            # Split the line on whitespace
        number, value = line.split()
            # construct the SQL statement
        sql = ("""INSERT INTO popularity (PersonNumber, Category, Value)
                VALUES(%s, %s, %s)""", (number, Category, value))
            # execute the query
        cursor.execute(sql)

connection = MySQLdb.connect(host='localhost', user='root', \
                                 passwd='password', db='dogs')

cursor = connection.cursor()

Category = 'dogs'
insert_popularity(Category, 'dogs.txt', cursor)
connection.commit()
cursor.close()
connection.close()

回答1:

Just do it simply, one thing at a time, no fancy stuff that is error prone and slows the reader down while they navigate the obfuscation:

sql = """INSERT INTO popularity (PersonNumber, Category, Value) VALUES (%s, %s, %s)"""
args = (number, Category, value)
cursor.execute(sql, args)

Your comment (execute the query) went away because (a) it was wrong (insert != query) and (b) the fixed version (execute the insertion) would be quite redundant given the clarity of the fixed code.

Update after new problem (too many values to unpack):

Instead of this code:

for line in txt_file:
        # Split the line on whitespace
    number, value = line.split()

do this:

for lino, line in enumerate(txt_file, 1):
    pieces = line.split()
    if len(pieces) != 2:
        print "Bad data in line %d: %r" % (lino, pieces)
        continue
    number, value = pieces

回答2:

You've created the query to execute as a tuple. There two possibilities to solve this:

1. Use the created query (sql) as a list of arguments:

   sql = ("""INSERT INTO popularity (PersonNumber, Category, Value) VALUES(%s, %s, %s)""", (number, Category, value)) # execute the query cursor.execute(*sql)

2. Directly add the query to the execute method:

   cursor.execute("""INSERT INTO popularity (PersonNumber, Category, Value) VALUES(%s, %s, %s)""", (number, Category, value))

Number 2 is definitely a better option than the first one. Thanks to all comments!

回答3:

What are the data types of the number, category, and data? If any of these are strings, then you should wrap them in single quotes in your query.

回答4:

Do not take me wrong, but the code is very messed up...

1. the return inside the for loop will return the first splited string in the first line.
2. open_file is defined but never called

and so on...

My take would be something like:

def process_file(category, filename, cursor):
    txt_file = file(filename, 'r')
    for line in txt_file:
        number, value = line.split()
        sql = ("""INSERT INTO popularity (PersonNumber, Category, Value)
            VALUES(%s, %s, %s)""", (number, category, data))
        cursor.execute(sql)

connection = MySQLdb.connect(host='localhost', user='root',
                         passwd='password', db='inb104')
# get a cursor on the database
cursor = connection.cursor()
category = 'foo'
process_file(category, 'somefile.txt', cursor)
# commit the changes to the database\
connection.commit()
# close the cursor and connection
cursor.close()
connection.close()

回答5:

Try it like this:

def insert_popularity(Category, filename, cursor):
    sql = """INSERT INTO popularity (PersonNumber, Category, Value)
           VALUES(%s, %s, %s)"""

    txt_file = file(filename, 'r')
    for line in txt_file:
        # Split the line on whitespace
        number, value = line.split()
        # execute the query
        cursor.execute(sql, (number, Category, value))
    txt_file.close()

connection = MySQLdb.connect(host='localhost', user='root', \
                                 passwd='password', db='dogs')

cursor = connection.cursor()

Category = 'dogs'
insert_popularity(Category, 'dogs.txt', cursor)

connection.commit()
cursor.close()
connection.close()

Also note: your code suggests this is a MySQL database; if it's an SQLite database, like the title of your question says, please substitute '?' for every '%s' in the sql statement.

来源：https://stackoverflow.com/questions/6148293/i-would-like-some-advice-why-this-would-not-insert-data-into-my-sql-table