/**
     * Static factory to retrieve a type 4 (pseudo randomly generated) UUID.
     *
     * The {@code UUID} is generated using a cryptographically strong pseudo
     * random number generator.
     *
     * @return  A randomly generated {@code UUID}
     */
    public static UUID randomUUID() {
        SecureRandom ng = Holder.numberGenerator;

        byte[] randomBytes = new byte[16];
        ng.nextBytes(randomBytes);
        randomBytes[6]  &= 0x0f;  /* clear version        */
        randomBytes[6]  |= 0x40;  /* set to version 4     */
        randomBytes[8]  &= 0x3f;  /* clear variant        */
        randomBytes[8]  |= 0x80;  /* set to IETF variant  */
        return new UUID(randomBytes);
    }

    /**
     * Static factory to retrieve a type 3 (name based) {@code UUID} based on
     * the specified byte array.
     *
     * @param  name
     *         A byte array to be used to construct a {@code UUID}
     *
     * @return  A {@code UUID} generated from the specified array
     */
    public static UUID nameUUIDFromBytes(byte[] name) {
        MessageDigest md;
        try {
            md = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException nsae) {
            throw new InternalError("MD5 not supported", nsae);
        }
        byte[] md5Bytes = md.digest(name);
        md5Bytes[6]  &= 0x0f;  /* clear version        */
        md5Bytes[6]  |= 0x30;  /* set to version 3     */
        md5Bytes[8]  &= 0x3f;  /* clear variant        */
        md5Bytes[8]  |= 0x80;  /* set to IETF variant  */
        return new UUID(md5Bytes);
    }

UUID uuid1 = UUID.nameUUIDFromBytes(new byte[]{'a', 'b', 'c'});
System.out.println("uuid1 = " + uuid1);
UUID uuid2 = UUID.nameUUIDFromBytes(new byte[]{'a', 'b', 'c'});
System.out.println("uuid2 = " + uuid2);
UUID uuid3 = UUID.randomUUID();
System.out.println("uuid3 = " + uuid3);
UUID uuid4 = UUID.randomUUID();
System.out.println("uuid4 = " + uuid4);
uuid1 = 90015098-3cd2-3fb0-9696-3f7d28e17f72
uuid2 = 90015098-3cd2-3fb0-9696-3f7d28e17f72
uuid3 = 2fd31523-bffb-4a7d-8cb9-a8b9c398822e
uuid4 = af06ce71-6da4-4fdc-bc2b-096c99dbaba5

SET @ori_u = UUID();
SET @u = REPLACE(@ori_u,'-','');
INSERT INTO uuid_test (id) VALUES (UNHEX(CONCAT(SUBSTR(@u, 15, 4),
                                                SUBSTR(@u, 10, 4),
                                                SUBSTR(@u, 1, 8),
                                                SUBSTR(@u, 20, 4),
                                                SUBSTR(@u, 25))));
SELECT HEX(id) FROM uuid_test;
+----------------------------------+
| HEX(id)                          |
+----------------------------------+
| EBB63D31510A7E23C024AC1100020000 |
| EBB63D3167F6128CC024AC1100020000 |
| EBB63D31B7B69C9DC024AC1100020000 |
+----------------------------------+
-- 使用MySQL8提供的函数验证
SELECT BIN_TO_UUID(id) FROM uuid_test;
+--------------------------------------+
| BIN_TO_UUID(id)                      |
+--------------------------------------+
| ebb63d31-510a-7e23-c024-ac1100020000 |
| ebb63d31-67f6-128c-c024-ac1100020000 |
| ebb63d31-b7b6-9c9d-c024-ac1100020000 |
+--------------------------------------+

CREATE TABLE t (id binary(16) PRIMARY KEY);

INSERT INTO t VALUES(UUID_TO_BIN(UUID(),1));

SELECT BIN_TO_UUID(id,0) FROM t;
+--------------------------------------+
| BIN_TO_UUID(id,0)                    |
+--------------------------------------+
| 11ebb3d1-b04a-0277-b69c-0242ac110002 |
| 11ebb3d1-b0f3-c8eb-b69c-0242ac110002 |
| 11ebb3d1-b198-be16-b69c-0242ac110002 |
+--------------------------------------+