參考:
http://stackoverflow.com/questions/412341/how-should-i-store-guid-in-mysql-tables
通常用UUID做唯一標識,需要在數據庫中進行存儲。
UUID的格式
String string = UUID.randomUUID().toString();
System.out.println("uuid:" + string);
uuid:05ba463f-1dab-471f-81c7-58e0b06f35f0數據庫中直接存儲UUID的壞處:
DELIMITER $$
CREATE FUNCTION `GuidToBinary`(
$Data VARCHAR(36)
) RETURNS binary(16)
BEGIN
DECLARE $Result BINARY(16) DEFAULT NULL;
IF $Data IS NOT NULL THEN
SET $Data = REPLACE($Data,'-','');
SET $Result = CONCAT(UNHEX(SUBSTRING($Data,7,2)),UNHEX(SUBSTRING($Data,5,2)),UNHEX(SUBSTRING($Data,3,2)), UNHEX(SUBSTRING($Data,1,2)),
UNHEX(SUBSTRING($Data,11,2)),UNHEX(SUBSTRING($Data,9,2)),UNHEX(SUBSTRING($Data,15,2)) , UNHEX(SUBSTRING($Data,13,2)),
UNHEX(SUBSTRING($Data,17,16)));
END IF;
RETURN $Result;
END
$$
CREATE FUNCTION `ToGuid`(
$Data BINARY(16)
) RETURNS char(36) CHARSET utf8
BEGIN
DECLARE $Result CHAR(36) DEFAULT NULL;
IF $Data IS NOT NULL THEN
SET $Result = CONCAT(HEX(SUBSTRING($Data,4,1)),HEX(SUBSTRING($Data,3,1)),HEX(SUBSTRING($Data,2,1)), HEX(SUBSTRING($Data,1,1)) , '-',
HEX(SUBSTRING($Data,6,1)),HEX(SUBSTRING($Data,5,1)),'-',
HEX(SUBSTRING($Data,8,1)) , HEX(SUBSTRING($Data,7,1)),'-',
HEX(SUBSTRING($Data,9,2)),'-',HEX(SUBSTRING($Data,11,6)));
END IF;
RETURN $Result;
END
CREATE FUNCTION `UUIDTOBIN`() RETURNS binary(16)
BEGIN
DECLARE my_uuid char(36);
SET my_uuid = UUID();
RETURN CONCAT(UNHEX(LEFT(my_uuid,8)),UNHEX(MID(my_uuid,10,4)),UNHEX(MID(my_uuid,15,4)),UNHEX(MID(my_uuid,20,4)),UNHEX(RIGHT(my_uuid,12)));
END
CREATE FUNCTION `BINTOUUID`(UUID BINARY(16)) RETURNS char(36)
BEGIN
RETURN CONCAT(HEX(LEFT(uuid,4)),'-', HEX(MID(uuid,5,2)),'-', HEX(MID(uuid,7,2)),'-',HEX(MID(uuid,9,2)),'-',HEX(RIGHT(uuid,6)));
END