When an SQL trigger modifies the F1 field in the test table, it also modifies the F2 field according to the condition.

Code
-- When the F1 field in the test table is modified, the F2 field is also modified according to the condition.
Alter   Trigger   [ DBO ] . [ Updatetest1 ]   On   [ DBO ] . [ Test ]  
For   Insert , Update , Delete  
As
Begin

If Update(F1)
 Declare
 @ FID Int,
 @ F1 Int 

Set   @ FID = ( Select FID From Inserted) -- Obtain the ID of the modified row
Set   @ F1 = ( Select F1 From Inserted) -- Get modified content

Begin
If ( Select F1 From Inserted) >   0
Begin
Update Test Set F2 =   ' 5 '   Where FID =   @ FID
End
If ( Select F1 From Inserted) <=   0
Begin
Update Test Set F2 =   ' 6 '   Where FID =   @ FID
End
End
End

An example of triggering an SQL statement by modifying a field