psycopg2 커서에서 열 이름 목록을 어떻게 얻습니까?

선택한 열 이름에서 직접 열 레이블을 생성하는 일반적인 방법을 원하고 python의 psycopg2 모듈이이 기능을 지원한다는 것을 기억하십시오.

Mark Lutz의 "Programming Python"에서 :

curs.execute("Select * FROM people LIMIT 0")
colnames = [desc[0] for desc in curs.description]

당신이 할 수있는 또 다른 일은 열을 이름으로 참조 할 수있는 커서를 만드는 것입니다 (처음에는이 페이지로 이동해야합니다).

import psycopg2
from psycopg2.extras import RealDictCursor

ps_conn = psycopg2.connect(...)
ps_cursor = psql_conn.cursor(cursor_factory=RealDictCursor)

ps_cursor.execute('select 1 as col_a, 2 as col_b')
my_record = ps_cursor.fetchone()
print (my_record['col_a'],my_record['col_b'])

>> 1, 2

별도의 쿼리에서 열 이름 을 가져 오려면 information_schema.columns 테이블을 쿼리 할 수 ​​있습니다.

#!/usr/bin/env python3

import psycopg2

if __name__ == '__main__':
  DSN = 'host=YOUR_DATABASE_HOST port=YOUR_DATABASE_PORT dbname=YOUR_DATABASE_NAME user=YOUR_DATABASE_USER'

  column_names = []

  with psycopg2.connect(DSN) as connection:
      with connection.cursor() as cursor:
          cursor.execute("select column_name from information_schema.columns where table_schema = 'YOUR_SCHEMA_NAME' and table_name='YOUR_TABLE_NAME'")
          column_names = [row[0] for row in cursor]

  print("Column names: {}\n".format(column_names))

data rows와 동일한 쿼리에서 열 이름 을 가져 오려면 커서의 description 필드를 사용할 수 있습니다.

#!/usr/bin/env python3

import psycopg2

if __name__ == '__main__':
  DSN = 'host=YOUR_DATABASE_HOST port=YOUR_DATABASE_PORT dbname=YOUR_DATABASE_NAME user=YOUR_DATABASE_USER'

  column_names = []
  data_rows = []

  with psycopg2.connect(DSN) as connection:
    with connection.cursor() as cursor:
      cursor.execute("select field1, field2, fieldn from table1")
      column_names = [desc[0] for desc in cursor.description]
      for row in cursor:
        data_rows.append(row)

  print("Column names: {}\n".format(column_names))

db 쿼리에서 명명 된 튜플 obj를 원한다면 다음 스 니펫을 사용할 수 있습니다.

from collections import namedtuple

def create_record(obj, fields):
    ''' given obj from db returns named tuple with fields mapped to values '''
    Record = namedtuple("Record", fields)
    mappings = dict(zip(fields, obj))
    return Record(**mappings)

cur.execute("Select * FROM people")
colnames = [desc[0] for desc in cur.description]
rows = cur.fetchall()
cur.close()
result = []
for row in rows:
    result.append(create_record(row, colnames))

이를 통해 클래스 속성 인 것처럼 레코드 값에 액세스 할 수 있습니다.

record.id, record.other_table_column_name 등

또는 더 짧은

from psycopg2.extras import NamedTupleCursor
with cursor(cursor_factory=NamedTupleCursor) as cur:
   cur.execute("Select * ...")
   return cur.fetchall()

2.7로 작성된 Python 스크립트에 따라 SQL 쿼리 쓰기를 실행 한 후

total_fields = len(cursor.description)    
fields_names = [i[0] for i in cursor.description   
    Print fields_names

난 당신이 사용해야하는 것으로 나타났습니다 cursor.fetchone()에 열 목록을 얻을 수있는 쿼리 후 cursor.description(IE에서 [desc[0] for desc in curs.description])

나는 또한 비슷한 문제에 직면했다. 나는 이것을 해결하기 위해 간단한 트릭을 사용합니다. 다음과 같은 목록에 열 이름이 있다고 가정하십시오.

col_name = ['a', 'b', 'c']

그럼 당신은 다음을 수행 할 수 있습니다

for row in cursor.fetchone():
    print zip(col_name, row)

 # You can use this function
 def getColumns(cursorDescription):
     columnList = []
     for tupla in cursorDescription:
         columnList.append(tupla[0])
     return columnList 

#!/usr/bin/python
import psycopg2
#note that we have to import the Psycopg2 extras library!
import psycopg2.extras
import sys

def main():
    conn_string = "host='localhost' dbname='my_database' user='postgres' password='secret'"
    # print the connection string we will use to connect
    print "Connecting to database\n ->%s" % (conn_string)

    # get a connection, if a connect cannot be made an exception will be raised here
    conn = psycopg2.connect(conn_string)

    # conn.cursor will return a cursor object, you can use this query to perform queries
    # note that in this example we pass a cursor_factory argument that will
    # dictionary cursor so COLUMNS will be returned as a dictionary so we
    # can access columns by their name instead of index.
    cursor = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)

    # tell postgres to use more work memory
    work_mem = 2048

    # by passing a tuple as the 2nd argument to the execution function our
    # %s string variable will get replaced with the order of variables in
    # the list. In this case there is only 1 variable.
    # Note that in python you specify a tuple with one item in it by placing
    # a comma after the first variable and surrounding it in parentheses.
    cursor.execute('SET work_mem TO %s', (work_mem,))

    # Then we get the work memory we just set -> we know we only want the
    # first ROW so we call fetchone.
    # then we use bracket access to get the FIRST value.
    # Note that even though we've returned the columns by name we can still
    # access columns by numeric index as well - which is really nice.
    cursor.execute('SHOW work_mem')

    # Call fetchone - which will fetch the first row returned from the
    # database.
    memory = cursor.fetchone()

    # access the column by numeric index:
    # even though we enabled columns by name I'm showing you this to
    # show that you can still access columns by index and iterate over them.
    print "Value: ", memory[0]

    # print the entire row 
    print "Row: ", memory

if __name__ == "__main__":
    main()