python, mysql, inserting string into table, error 1054

Question

I am having the problem OperationalError: (1054, "Unknown column 'Ellie' in 'field list'") With the code below, I'm trying to insert data from json into a my sql database. The problem happens whenever I try to insert a string in this case "Ellie" This is something do to with string interpolation I think but I cant get it to work despite trying some other solutions I have seen here..

CREATE TABLE

con = MySQLdb.connect('localhost','root','','tweetsdb01')
cursor = con.cursor()
cursor.execute("CREATE TABLE IF NOT EXISTS User(user_id BIGINT NOT NULL PRIMARY KEY, username varchar(25) NOT NULL,user varchar(25) NOT NULL) CHARACTER SET utf8 COLLATE utf8_unicode_ci ENGINE=InnoDB")
con.commit() 

INSERT INTO

def populate_user(a,b,c):
    con = MySQLdb.connect('localhost','root','','tweetsdb01')
    cursor = con.cursor()
    cursor.execute("INSERT INTO User(user_id,username,user) VALUES(%s,%s,%s)"%(a,b,c))
    con.commit() 
    cursor.close() 

READ FILE- this calls the populate method above

def read(file):
    json_data=open(file)
    tweets = []
    for i in range(10):
        tweet = json.loads(json_data.readline())

    populate_user(tweet['from_user_id'],tweet['from_user_name'],tweet['from_user'])

Answer 1

Use parametrized SQL:

cursor.execute("INSERT INTO User(user_id,username,user) VALUES (%s,%s,%s)", (a,b,c))

(Notice the values (a,b,c) are passed to the function execute as a second argument, not as part of the first argument through string interpolation). MySQLdb will properly quote the arguments for you.

---

PS. As Vajk Hermecz notes, the problem occurs because the string 'Ellie' is not being properly quoted.

When you do the string interpolation with "(%s,)" % (a,) you get (Ellie,) whereas what you really want is ('Ellie',). But don't bother doing the quoting yourself. It is safer and easier to use parametrized SQL.