MySQL: convert GUID (UUID) to BINARY(16)

uuid_to_bin.sql

# MySQL: convert GUID (Microsoft-style UUID) to BINARY(16)
# '11223344-5566-7788-9900-AABBCCDDEEFF' → 0x44332211665588779900AABBCCDDEEFF
# usage: CREATE TABLE example(id INT NOT NULL PRIMARY KEY AUTO_INCREMENT, guid BINARY(16) NOT NULL UNIQUE);
#        INSERT INTO example(guid) VALUES (uuid_to_bin(UUID()));

CREATE FUNCTION uuid_to_bin(s CHAR(36))
  RETURNS binary(16)
  DETERMINISTIC
RETURN UNHEX(CONCAT(
  SUBSTRING(s,7,2),SUBSTRING(s,5,2),SUBSTRING(s,3,2),SUBSTRING(s,1,2),
  SUBSTRING(s,12,2),SUBSTRING(s,10,2),
  SUBSTRING(s,17,2),SUBSTRING(s,15,2),
  SUBSTRING(s,20,4),
  SUBSTRING(s,25,12)
  ));