6
MySQL的UUID
函數返回一個UUIDv1 GUID。我正在尋找一種簡單的方法來生成SQL中的隨機GUID(即UUIDv4)。如何在MySQL中生成UUIDv4?
MySQL的UUID
函數返回一個UUIDv1 GUID。我正在尋找一種簡單的方法來生成SQL中的隨機GUID(即UUIDv4)。如何在MySQL中生成UUIDv4?
我花了相當一段時間尋找解決方案,並提出了以下 mysql函數,該函數使用標準MySQL 函數生成隨機UUID(即UUIDv4)。我正在回答我自己的問題,希望分享 有用。
-- Change delimiter so that the function body doesn't end the function declaration
DELIMITER //
CREATE FUNCTION uuid_v4()
RETURNS CHAR(36)
BEGIN
-- Generate 8 2-byte strings that we will combine into a UUIDv4
SET @h1 = LPAD(HEX(FLOOR(RAND() * 0xffff)), 4, '0');
SET @h2 = LPAD(HEX(FLOOR(RAND() * 0xffff)), 4, '0');
SET @h3 = LPAD(HEX(FLOOR(RAND() * 0xffff)), 4, '0');
SET @h6 = LPAD(HEX(FLOOR(RAND() * 0xffff)), 4, '0');
SET @h7 = LPAD(HEX(FLOOR(RAND() * 0xffff)), 4, '0');
SET @h8 = LPAD(HEX(FLOOR(RAND() * 0xffff)), 4, '0');
-- 4th section will start with a 4 indicating the version
SET @h4 = CONCAT('4', LPAD(HEX(FLOOR(RAND() * 0x0fff)), 3, '0'));
-- 5th section first half-byte can only be 8, 9 A or B
SET @h5 = CONCAT(HEX(FLOOR(RAND() * 4 + 8)),
LPAD(HEX(FLOOR(RAND() * 0x0fff)), 3, '0'));
-- Build the complete UUID
RETURN LOWER(CONCAT(
@h1, @h2, '-', @h3, '-', @h4, '-', @h5, '-', @h6, @h7, @h8
));
END
//
-- Switch back the delimiter
DELIMITER ;
注:使用的僞隨機數生成(MySQL的RAND
)不 加密安全,因而具有一定的偏差,可以提高碰撞 風險。