scrollable_cursors.py

# -----------------------------------------------------------------------------
# Copyright (c) 2016, 2025, Oracle and/or its affiliates.
#
# Portions Copyright 2007-2015, Anthony Tuininga. All rights reserved.
#
# Portions Copyright 2001-2007, Computronix (Canada) Ltd., Edmonton, Alberta,
# Canada. All rights reserved.
#
# This software is dual-licensed to you under the Universal Permissive License
# (UPL) 1.0 as shown at https://oss.oracle.com/licenses/upl and Apache License
# 2.0 as shown at http://www.apache.org/licenses/LICENSE-2.0. You may choose
# either license.
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# the following applies:
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# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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# https://www.apache.org/licenses/LICENSE-2.0
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
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# -----------------------------------------------------------------------------

# -----------------------------------------------------------------------------
# scrollable_cursors.py
#
# Demonstrates how to use scrollable cursors. These allow moving forward and
# backward in the result set but incur additional overhead on the server to
# retain this information.
# -----------------------------------------------------------------------------

importoracledb
importsample_env

# determine whether to use python-oracledb thin mode or thick mode
ifnotsample_env.get_is_thin():
oracledb.init_oracle_client(lib_dir=sample_env.get_oracle_client())

connection=oracledb.connect(
user=sample_env.get_main_user(),
password=sample_env.get_main_password(),
dsn=sample_env.get_connect_string(),
)

# show all of the rows available in the table
withconnection.cursor() ascursor:
cursor.execute("select * from TestStrings order by IntCol")
print("ALL ROWS")
forrowincursor:
print(row)
print()

# create a scrollable cursor
withconnection.cursor(scrollable=True) ascursor:
# set array size smaller than the default (100) to force scrolling by the
# database; otherwise, scrolling occurs directly within the buffers
cursor.arraysize=3
cursor.execute("select * from TestStrings order by IntCol")

# scroll to last row in the result set; the first parameter is not needed
# and is ignored)
cursor.scroll(mode="last")
print("LAST ROW")
print(cursor.fetchone())
print()

# scroll to the first row in the result set; the first parameter not needed
# and is ignored
cursor.scroll(mode="first")
print("FIRST ROW")
print(cursor.fetchone())
print()

# scroll to an absolute row number
cursor.scroll(5, mode="absolute")
print("ROW 5")
print(cursor.fetchone())
print()

# scroll forward six rows (the mode parameter defaults to relative)
cursor.scroll(3)
print("SKIP 3 ROWS")
print(cursor.fetchone())
print()

# scroll backward four rows (the mode parameter defaults to relative)
cursor.scroll(-4)
print("SKIP BACK 4 ROWS")
print(cursor.fetchone())
print()