mysql.connector.ProgrammingError in Python when insert data to table - mysql

Question

I am writing a script to read data from a file by lines and insert each line into MySQL database. I use mysql.connector to do this. Here is a piece of script.
def insert_query(data):
return ("INSERT INTO " + tblname + " (`log`) " + "VALUES " + "(" + "'" + data + "'" + ")")
with open('data.txt', 'r') as f:
lines = f.readlines()
for line in lines:
add_line = insert_query(line)
cursor.execute(add_line)
cursor.commit()
File data.txt has size is 5Mbyte, but it has about 10000 lines.
tblname has 2 field: ID - INT (11) (auto-increment) , log - TEXT
When i run this script, it add to database about 100 lines and crashed. It report a error:
mysql.connector.errors.ProgrammingError: 1064 (42000): You have an
error in your SQL syntax; check the manual that corresponds to your
MySQL server version for ')'
MySQL version : 5.5.27
How to solve this problem ? Thanks.

Answer 1

Your insert statement is incorrect: 'tblname' is undefined in your function, hence the syntax error. However, there are bigger issues with how you solve it: what if a line in the log has quotes and brackets?
The following code show how to read data from a file and insert it line by line:
stmt = "INSERT INTO {table} (c1) VALUES (%s)".format(table=table_name)
with open('data.txt', 'r') as fp:
for line in fp:
data = (line.strip(),)
cur.execute(stmt, (line.strip(),))
cnx.commit()
Or using executemany(), which would be faster:
with open('data.txt', 'r') as fp:
cur.executemany(stmt, [(line.strip(),) for line in fp])
cnx.commit()