sqlserver trigger（触发器）-更新某几列数据时触发【转】

CREATE TRIGGER [dbo].[updataAlarmLevel]
ON [dbo].[Alarm_Alarm_Info]
AFTER INSERT, UPDATE – 在更新和插入之后
AS
BEGIN
if update(transferNum) or update(potentialLoss)–如果Alarm_Alarm_Info表中的transferNum或potentialLoss两列发生改变所触发的事件；  或者用 or
declare @transferNum int;
declare @potentialLoss decimal(20,2);
declare @alarmLeve int;
select @transferNum=transferNum from inserted;--inserted表示当前修改的数据行
select @potentialLoss=potentialLoss from inserted;
if @transferNum > 1000 or @potentialLoss > 100000000 --if条件不需要{}
set @alarmLeve = 1;--特大型警情
else if 500 < @transferNum and @transferNum <= 1000 or @potentialLoss <= 100000000 and @potentialLoss > 50000000
set @alarmLeve = 2;--大型警情
else if 100 < @transferNum and @transferNum <= 500 or @potentialLoss > 5000000 and @potentialLoss <= 50000000
set @alarmLeve = 3;--中型警情
else if @transferNum <= 100 or @potentialLoss <= 5000000
set @alarmLeve = 4;--小型警情
update Alarm_Alarm_Info set alarmLevel = @alarmLeve where id = (select id from inserted);
END