mirror of
https://github.com/psycopg/psycopg2.git
synced 2024-09-21 11:18:49 +03:00
82 lines
2.5 KiB
Python
82 lines
2.5 KiB
Python
# fetch.py -- example about declaring cursors
|
|
#
|
|
# Copyright (C) 2001-2005 Federico Di Gregorio <fog@debian.org>
|
|
#
|
|
# This program is free software; you can redistribute it and/or modify
|
|
# it under the terms of the GNU General Public License as published by the
|
|
# Free Software Foundation; either version 2, or (at your option) any later
|
|
# version.
|
|
#
|
|
# This program is distributed in the hope that it will be useful, but
|
|
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY
|
|
# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
# for more details.
|
|
#
|
|
|
|
## put in DSN your DSN string
|
|
|
|
DSN = 'dbname=test'
|
|
|
|
## don't modify anything below tis line (except for experimenting)
|
|
|
|
import sys
|
|
import psycopg2
|
|
|
|
if len(sys.argv) > 1:
|
|
DSN = sys.argv[1]
|
|
|
|
print "Opening connection using dns:", DSN
|
|
conn = psycopg2.connect(DSN)
|
|
print "Encoding for this connection is", conn.encoding
|
|
|
|
curs = conn.cursor()
|
|
try:
|
|
curs.execute("CREATE TABLE test_fetch (val int4)")
|
|
except:
|
|
conn.rollback()
|
|
curs.execute("DROP TABLE test_fetch")
|
|
curs.execute("CREATE TABLE test_fetch (val int4)")
|
|
conn.commit()
|
|
|
|
# we use this function to format the output
|
|
|
|
def flatten(l):
|
|
"""Flattens list of tuples l."""
|
|
return map(lambda x: x[0], l)
|
|
|
|
# insert 20 rows in the table
|
|
|
|
for i in range(20):
|
|
curs.execute("INSERT INTO test_fetch VALUES(%s)", (i,))
|
|
conn.commit()
|
|
|
|
# does some nice tricks with the transaction and postgres cursors
|
|
# (remember to always commit or rollback before a DECLARE)
|
|
#
|
|
# we don't need to DECLARE ourselves, psycopg now support named
|
|
# cursors (but we leave the code here, comments, as an example of
|
|
# what psycopg is doing under the hood)
|
|
#
|
|
#curs.execute("DECLARE crs CURSOR FOR SELECT * FROM test_fetch")
|
|
#curs.execute("FETCH 10 FROM crs")
|
|
#print "First 10 rows:", flatten(curs.fetchall())
|
|
#curs.execute("MOVE -5 FROM crs")
|
|
#print "Moved back cursor by 5 rows (to row 5.)"
|
|
#curs.execute("FETCH 10 FROM crs")
|
|
#print "Another 10 rows:", flatten(curs.fetchall())
|
|
#curs.execute("FETCH 10 FROM crs")
|
|
#print "The remaining rows:", flatten(curs.fetchall())
|
|
|
|
ncurs = conn.cursor("crs")
|
|
ncurs.execute("SELECT * FROM test_fetch")
|
|
print "First 10 rows:", flatten(ncurs.fetchmany(10))
|
|
ncurs.scroll(-5)
|
|
print "Moved back cursor by 5 rows (to row 5.)"
|
|
print "Another 10 rows:", flatten(ncurs.fetchmany(10))
|
|
print "Another one:", list(ncurs.fetchone())
|
|
print "The remaining rows:", flatten(ncurs.fetchall())
|
|
conn.rollback()
|
|
|
|
curs.execute("DROP TABLE test_fetch")
|
|
conn.commit()
|