Question

I tried to fill a table in a database using MySQLdb. It did not give any errors, and once gave the warning

main.py:23: Warning: Data truncated for column 'other_id' at row 1
  cur.execute("INSERT INTO map VALUES(%s,%s)",(str(info[0]).replace('\n',''), str(info[2].replace('\n','').replace("'",""))))

so I thought it was working fine. However, when it was finished and I did a row count it turned out that nothing was added. Why was the data not added to the database? The code is below

def fillDatabase():
    db = MySQLdb.connect(host="127.0.0.1", 
                         user="root", 
                         passwd="", 
                         db="uniprot_map") 

    cur = db.cursor() 
    conversion_file = open('idmapping.dat')
    for line in conversion_file:
        info = line.split('\t')
        cur.execute("INSERT INTO map VALUES(%s,%s)",(str(info[0]).replace('\n',''), str(info[2].replace('\n','').replace("'",""))))

def test():
    db = MySQLdb.connect(host="127.0.0.1", 
                         user="root", 
                         passwd="", 
                         db="uniprot_map") 

    cur = db.cursor() 
    cur.execute("SELECT COUNT(*) FROM map")
    rows = cur.fetchall()

    for row in rows:
        print row

def main():
    fillDatabase()
    test()

Answer 1

You need to do a db.commit() after adding all of the entries. Even if the update is not transactional, the DBAPI imposes an implicit transaction on every change.