[EMAIL PROTECTED] wrote:
> I need to go through each line of a CSV file, and extract some fields
> using a regex. Then, I need to check each retrieved field, and if it
> looks like "", turn this into NULL so that it's correct SQL.
You are taking the wrong approach here.
Don't build SQL statements as strings; you are enabling the next SQL
injection attack. Pass parameters using the DB API instead.
Don't use regular expressions to parse a CSV file. Python's csv module is
more likely to deal correctly with the quirks of that standard.
A self-contained example:
import csv
import sqlite3 as sqlite
from cStringIO import StringIO
def records(infile):
for row in csv.reader(infile):
# replace empty strings in the second column with None
# which translates to NULL in the database
yield row[0], row[1] or None
def main():
# create sample data; you may use a real file
infile = StringIO("""\
alpha,beta,gamma
zeta,,theta
""")
# create the database
db = sqlite.connect(":memory:")
cursor = db.cursor()
cursor.execute("create table demo (first, second);")
# safely insert data
cursor.executemany("insert into demo values (?, ?);", records(infile))
# show contents
for row in cursor.execute("select first, second, second is NULL "
"from demo order by first, second;"):
print row
if __name__ == "__main__":
main()
Peter
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