Syntax:
CREATE_DIGEST(digest_type, str)

Creates a digest from the given string using the given digest type, and
returns the digest as a binary string. If digest generation fails, the
result is NULL.

Supported digest_type values: 'SHA224', 'SHA256', 'SHA384', 'SHA512'

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

