Syntax:
SHA1(str), SHA(str)

Calculates an SHA-1 160-bit checksum for the string, as described in
RFC 3174 (Secure Hash Algorithm). The value is returned as a binary
string of 40 hex digits, or NULL if the argument was NULL. One of the
possible uses for this function is as a hash key. You can also use it
as a cryptographic function for storing passwords. SHA() is synonymous
with SHA1().

URL: http://dev.mysql.com/doc/refman/5.1/en/encryption-functions.html

