An upgrade to MySQL version 4.1 or later can cause compatibility
issues for applications that use
PASSWORD() to generate passwords
for their own purposes. Applications really should not do this,
PASSWORD() should be used
only to manage passwords for MySQL accounts. But some
their own purposes anyway.
If you upgrade to 4.1 or later from a pre-4.1 version of MySQL
and run the server under conditions where it generates long
password hashes, an application using
PASSWORD() for its own passwords
breaks. The recommended course of action in such cases is to
modify the application to use another function, such as
MD5(), to produce hashed values.
If that is not possible, you can use the
OLD_PASSWORD() function, which is
provided for generate short hashes in the old format. However,
you should note that
OLD_PASSWORD() may one day no
longer be supported.
PHP programmers migrating their MySQL databases from version 4.0 or lower to version 4.1 or higher should see Section 21.9, “MySQL PHP API”.