How do I get a list of column names from a psycopg2 cursor?

Question

I would like a general way to generate column labels directly from the selected column names, and recall seeing that python\'s psycopg2 module supports this feature.

Answer 1

I have noticed that you must use cursor.fetchone() after the query to get the list of columns in cursor.description (i.e in [desc[0] for desc in curs.description])

Answer 2

From "Programming Python" by Mark Lutz:

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

Answer 3

If you're looking to get a pandas data frame with column headers already associated, try this:

import psycopg2, pandas

con=psycopg2.connect(
    dbname=DBNAME, 
    host=HOST, 
    port=PORT, 
    user=USER, 
    password=PASSWORD
)

sql = """
select * from x
"""

d = pandas.read_sql_query(sql,con)

con.close()

print(type(d))

print(pandas.DataFrame.head(d))

Answer 4

To get the column names in a separate query, you can query the information_schema.columns table.

#!/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))

To get column names in the same query as data rows, you can use the description field of the cursor:

#!/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))

Answer 5

After executing SQL query write following python script written in 2.7

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

Answer 6

I also used to face similar issue. I use a simple trick to solve this. Suppose you have column names in a list like

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

Then you can do following

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