Depending on the context used, starts a new transaction or sets the mode for the default transaction on the database connection.
You can have at most 10 separate transactions per connection. There is no concept of 'nested transactions;' multiple calls will create independent and unrelated transactions. This allows you to write programs with logic that will be totally incomprehensible even to yourself. Don't do it.
Flag values for specifying transaction mode:
InterBase has an interesting feature that it supports transactions covering several different connections and databases, and this function actually takes up to 19 link parameters. However, support for this functionality has not yet been implemented and only the last link is used.
Available in PHP 3 since 3.0.7, PHP 4 since 4.0RC1
PHP Functions Essential Reference. Copyright © 2002 by New Riders Publishing (Authors: Zak Greant, Graeme Merrall, Torben Wilson, Brett Michlitsch). This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at http://www.opencontent.org/openpub/). The authors of this book have elected not to choose any options under the OPL. This online book was obtained from http://www.fooassociates.com/phpfer/ and is designed to provide information about the PHP programming language, focusing on PHP version 4.0.4 for the most part. The information is provided on an as-is basis, and no warranty or fitness is implied. All persons and entities shall have neither liability nor responsibility to any person or entity with respect to any loss or damage arising from the information contained in this book.