Merge from trunk

[plcapi.git] / trunk / psycopg2 / examples / fetch.py

diff --git a/trunk/psycopg2/examples/fetch.py b/trunk/psycopg2/examples/fetch.py
new file mode 100644 (file)
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+++ b/trunk/psycopg2/examples/fetch.py
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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 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()