python Postgresql：忽略csv文件中的最后一列

Question

I have problem with importing a CSV file. I am using postgresql's COPY FROM command to copy a CSV file into a 2-column table.

I have a CSV file in the following format;

"1";"A"
"2";"B"
"3";"C";"CAD450"
"4";"D";"ABX123"

I want to import all these lines of the CSV file into the table but I want to skip any extra added columns.

Currently I am skipping any lines that contain extra columns, for example here columns "1";"C";"CAD450" and "1";"D";"ABX123" are skipped and I am importing only the first two columns. But I want to copy all these four lines into my table. So is there any way where I can ignore the last column and copy all the four lines into my table, like this

"1";"A"
"1";"B"
"1";"C"
"1";"D"

Answer 1

用awk预处理文件以去除多余的列：

awk -F';' '{print $1 ";" $2 }' > new_file.csv

Answer 2

通过cut或awk配管（如上所述）比使用python / psycopg容易。

cat csv_file.csv | cut -d';' -f1,2 | psql -u USER DATABASE -c "COPY table FROM STDIN WITH DELIMITER ';';"

Answer 3

with open("file.csv","r") as f:
    t=[line.strip().split(";")[:2] for line in f]

Answer 4

Myriad ways to handle the problem.
I'd probably do something like this:

import csv
import psycopg2
dr = csv.DictReader(open('test.csv','rb'), 
                    delimiter=';',
                    quotechar='"',
                    fieldnames=['col1','col2']) # need not specify other cols
CONNSTR = """
  host=127.0.0.1 
  dbname=mydb
  user=me
  password=pw
  port=5432"""
cxn = psycopg2.connect(CONNSTR)
cur = cxn.cursor()
cur.execute("""CREATE TABLE from_csv (
               id serial NOT NULL,
               col1 character varying,
               col2 character varying,
               CONSTRAINT from_csv_pkey PRIMARY KEY (id));""")
cur.executemany("""INSERT INTO from_csv (col1,col2) 
                   VALUES (%(col1)s,%(col2)s);""", dr)
cxn.commit()