Calculates an SHA-1 160-bit checksum for the string, as described in
RFC 3174 (Secure Hash Algorithm). The value is returned as a string of
40 hexadecimal digits, or NULL if the argument was NULL. One of the
possible uses for this function is as a hash key. See the notes at the
beginning of this section about storing hash values efficiently. SHA()
is synonymous with SHA1().
The return value is a string in the connection character set.
mysql> SELECT SHA1('abc');