SQL Server Trigger Sample

CREATE TRIGGER TriggerName ON [TableName]
AFTER UPDATE
AS
IF UPDATE ([Column1]) OR UPDATE ([Column2])
UPDATE [TableName]
SET [Column3] = CAST(YEAR([ThingMonth]) AS VARCHAR(4))+ '.' + DBO.LPAD(CAST(MONTH([ThingMonth]) AS VARCHAR(4)),2,0)
WHERE [Column3] = '.'