A simple problem with the SQL Update trigger

The specific steps are as follows:

1. First of all, create a trigger, which requires an update trigger to be created on the addtable table, as shown in the following figure, and then go to the next step.

3. Next, change the data in the addtable table as shown in the following figure, and then proceed to the next step.

4. Then, after completing the above steps, you will find that the trigger is triggered and the text of the setting is output, as shown in the image below, and then enter the next step.

5. Subsequently, you only need to change create to alter, and then modify the logic, as shown in the following figure, and then enter the next step.

7. Finally, another test is performed to change the addtable table and it is found that after the update trigger is triggered, it is aborted due to data protection, as shown in the image below. In this way, the problem is solved.

select @inta=(value you want) from inserted (the inserted table is a backup of the data before the update) if (@abcd-@inta) @inta > else

update is to delete first, and then insert to compare the inserted and deleted values.

You can understand the update action in 2 steps, first delete, and then insert

So, the previous value is in deleted.

The last value is in inserted.

create trigger t_atdatestate_update

on list

for update

asif update(atdatestate)

begindeclare @b atdatestate nvarchar(200) - before the modification.

declare @s atdatestate nvarchar(200) - modified.

declare @s_id int

select @s atdatestate= atdatestate from inserted -- Get the modified state from the updated replica table (temporary table).

select @s id=id,@b atdatestate=atdatestate from deleted -- Get the original value from the temporarily deleted table.

if @s_atdatestate is null

beginset @s_atdatestate='0'

endif @b_atdatestate is null

beginset @b_atdatestate='0'

end--If it was 2,3,4 before the modification, the state is lowered Modify down and The modified state is not the same as before the modification.

if ((convert(int,@b_atdatestate)>=2 and convert(int,@s_atdatestate)@s_atdatestate))

begininsert into ,before_atdatestate,after_atdatestate,o_ip,o_type)

values(@s_id,@b_atdatestate,@s_atdatestate,'','The state is not normal, and it is lowered downward')

endif(convert(int,@b_atdatestate)<2) and ( convert(int,@s_atdatestate)>=2)

begininsert into ,before_atdatestate,after_atdatestate,o_ip,o_type)

values(@s_id,@b_atdatestate,@s_atdatestate,'','Elevated status')

endend