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+# 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 psycopg
+
+if len(sys.argv) > 1:
+ DSN = sys.argv[1]
+
+print "Opening connection using dns:", DSN
+conn = psycopg.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)
+
+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())
+
+# rollback to close the transaction
+
+conn.rollback()
+
+curs.execute("DROP TABLE test_fetch")
+conn.commit()