检测(自动递增)序列中的缺失值

我需要在我的SP中放置一种适合这些孔的方式(在示例中，我的孔为30001,30003 ....).我的问题是，如何在SP中检查某个值是否已被占用".我以为使用MySQL的LOOP.尝试过这样的事情:CREATE PROCEDURE teste()BEGINDECLARE p INT;DECLARE aux INT;SET p = 30000; label1: LOOP SELECT Port FROM Reg WHERE Port = p INTO aux; IF p = 50000 THEN LEAVE label1; END IF; IF aux IS NULL THEN -- aux-1 is not null, so I can verify the "next miminum available position" aux = aux - 1; LEAVE label1; ELSE SET p = p + 1; ITERATE label1; END IF; END LOOP label1; RETURN aux;END $$我的问题是获取结果值.如果我放置该RETURN语句，则会得到仅在FUNCTION上允许的信息.当我结束循环时，SELECT的结果始终为空.我该怎么办?解决方案 SELECT IFNULL(MIN(r1.Port) + 1, 30000) as minportFROM Reg r1LEFT JOIN Reg r2 ON r1.Port + 1 = r2.PortWHERE r2.Port IS NULL:I have a 'Port' INT column, which it's supposed to range from 30000 to 50000.So, I have a Stored Procedure inserting values (Port is NOT NULL). So I have to choose 'manually' the value storing on that field. Problem is, altough I can insert incrementally (30000,30001,30002....) at a certain point some entries are deleted (it becames 30000, 30002, 30004.... ) so there are holes to be set.I need to place in my SP a way to fit those holes (on the example I have they are 30001,30003 ....). My problem is how to check within the SP, if a certain value is already 'ocuppied'.The I thought using LOOP from MySQL. Tried something like this:CREATE PROCEDURE teste()BEGINDECLARE p INT;DECLARE aux INT;SET p = 30000; label1: LOOP SELECT Port FROM Reg WHERE Port = p INTO aux; IF p = 50000 THEN LEAVE label1; END IF; IF aux IS NULL THEN -- aux-1 is not null, so I can verify the "next miminum available position" aux = aux - 1; LEAVE label1; ELSE SET p = p + 1; ITERATE label1; END IF; END LOOP label1; RETURN aux;END $$My problem is obtaining a result value. If I place that RETURN statement I get the info that is only allowed on a FUNCTION. And the result from the SELECT is always null when I end the Loop.What can I do? 解决方案 SELECT IFNULL(MIN(r1.Port) + 1, 30000) as minportFROM Reg r1LEFT JOIN Reg r2 ON r1.Port + 1 = r2.PortWHERE r2.Port IS NULL: 这篇关于检测(自动递增)序列中的缺失值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！