Syntax:
OLD_PASSWORD(str)

OLD_PASSWORD() was added when the implementation of PASSWORD() was
changed in MySQL 4.1 to improve security. OLD_PASSWORD() returns the
value of the pre-4.1 implementation of PASSWORD() as a string, and is
intended to permit you to reset passwords for any pre-4.1 clients that
need to connect to your version MySQL 5.7 server without locking them
out. See http://dev.mysql.com/doc/refman/5.7/en/password-hashing.html.

The return value is a nonbinary string in the connection character set.

*Note*: Passwords that use the pre-4.1 hashing method are less secure
than passwords that use the native password hashing method and should
be avoided. Pre-4.1 passwords are deprecated and support for them is
removed in MySQL 5.7.5. Consequently, OLD_PASSWORD() is deprecated and
is removed in MySQL 5.7.5.

URL: http://dev.mysql.com/doc/refman/5.7/en/encryption-functions.html

