MySQL实现雪花Id函数

CREATE FUNCTION `SnowId`() RETURNS bigint(20)
BEGIN
	
	DECLARE b_current_time BIGINT;
	DECLARE b_time_tick BIGINT;
	DECLARE i_work_id INT;
	DECLARE i_work_id_big_length INT;
	DECLARE i_seq_big_length INT;
	DECLARE f_random FLOAT;
	
	DECLARE b_res BIGINT;
	
	SET i_work_id = 1;
	SET i_work_id_big_length = 4;
	SET i_seq_big_length = 8;
	SET b_current_time = (REPLACE(UNIX_TIMESTAMP(CURRENT_TIMESTAMP(3)),'.','')) + 0;
	SET b_time_tick = b_current_time - 1582136402000;
	SET f_random = RAND();
	
	SET b_res = b_time_tick * POWER(2, i_work_id_big_length + i_seq_big_length) + i_work_id * POWER(2, i_seq_big_length) + (5 + round((POWER(2, i_seq_big_length)-1) * f_random, 0));
	
	RETURN b_res;
END

CREATE PROCEDURE `TestSnowId` () 
BEGIN
	DECLARE i INT DEFAULT 1;
	CREATE TEMPORARY TABLE IF NOT EXISTS temp_numbers ( number BIGINT );
	WHILE i <= 5000 DO
	    INSERT INTO temp_numbers ( number ) VALUES (SnowId ());
		SET i = i + 1;
	END WHILE;
	SELECT * FROM temp_numbers;
	DROP TEMPORARY TABLE IF EXISTS temp_numbers;
END

SELECT SnowId();

CALL TestSnowId();