Get list of column names from an empty table

Question

I'm using Python's sqlite3 module and would like to get a list of all columns in a table when the table doesn't have any rows.

Normally, if I create a database like

import sqlite3

conn = sqlite3.connect(":memory:") 
c = conn.cursor()

# create the table schema
c.execute('''create table stocks
 (date text, trans text, symbol text,
  qty real, price real)''')

conn.commit()
c.close()

Then I can get the column names with something like

conn.row_factory = sqlite3.Row
c = conn.cursor()
c.execute('select * from stocks')
r = c.fetchone()
print r.keys()

The problem is, if the table is initially empty, c.fetchone() returns None. If there are rows committed, then I am able to get a list of the column names.

Is there another way to do it? I went through the official sqlite3 module documentation, but couldn't find anything useful in that regard.

I guess I could put some dummy data in the table, then retrieve the column names and then delete the row, but I was hoping there's a more elegant way to do it.

Edit:

Seems there are a few ways to do it:

1. Get the SQL that was used to create the table:

   c.execute("""SELECT sql FROM sqlite_master 
   WHERE tbl_name = 'stocks' AND type = 'table'""")
   

2. Use the PRAGMA statement from sqlite3:

   c.execute("PRAGMA table_info(stocks)")
   

3. Use the .description field of the Cursor object

   c.execute('select * from stocks')
   r=c.fetchone()
   print c.description
   

Of these, No.2 seems the simplest and most straight-forward. Thanks all for the help.

Answer 1

try with :

conn.row_factory = sqlite3.Row
c = conn.cursor()
c.execute('select * from stocks')
r = c.fetchone()
print c.description            # This will print the columns names

>>> (('date', None, None, None, None, None, None), ('trans', None, None, None, None, None, None), ('symbol', None, None, None, None, None, None), ('qty', None, None, None, None, None, None), ('price', None, None, None, None, None, None))

As explained here, only the first items of each 7-tuple is usefull.

Answer 2

import sqlite3
con=sqlite3.connect(":memory:")
c=con.cursor()
c.execute("select * from stocks")
fieldnames=[f[0] for f in c.description]