从函数** keywords为sql语句创建一个字符串

Question

I have a csv file 'users.csv' that looks like this:

AppID,Perm,LastLogon,Email,FirstName
jimmeny1,admin,today,jim5@zerlina.com,pop1
jimmeny2,admin,today,jim10@zerlina.com,pop2
jimmeny3,admin,today,jim6@zerlina.com,pop3

I created the below function to load any number of columns from a csv into a sqlite table:

import sqlite3, csv

def bulkload(file, **args):
    sqlite = sqlite3.connect('mydb.db')
    s1 = sqlite.cursor()
    cols_string = '('
    cols = []
    for i in args.iteritems():
        col = '{} {}'.format(i[0], i[1][1])
        cols.append(col)
    for x, i in enumerate(cols):
        if x != len(cols) - 1:
            cols_string += i + ','
        if x == len(cols) - 1:
            cols_string += i + ')'
    sql1 = "CREATE TABLE IF NOT EXISTS mytable {}".format(cols_string)
    s1.execute(sql1)

An example call to the function:

bulkload('users.csv', appid=(0, 'text'), perm=(1,'text'), email=(3,'text'))

Is there an easier or more elegant or simply more pythonic way to create the string 'cols_string' that declares the column names and storage classes?

Answer 1

You should replace the following

cols_string = '('
for x, i in enumerate(cols):
    if x != len(cols) - 1:
        cols_string += i + ','
    if x == len(cols) - 1:
        cols_string += i + ')'

with the following, which is more pythonic & faster too (due to ''.join() method)

cols_string = '(' + ','.join(cols) + ')'