convert decode oracle pl/sq to ms sql and help required on logic

• I have below oracle query need to converted to ms sql. I also want to add a record into journal table when a 

Update table1 target
set curr =
decode(
(     
    select efforts from (
    select source.efforts efforts
      from
      (    
        SELECT     a.aid,a.efforts,ab.lcs
            FROM     CIP a, DC ab
            WHERE    a id = ab.id
            AND    a.id = @id
      ) source
      where target.caseid = @caseidupd
      and target.aid = source.aid
    ) tmp, 0, tmp.efforts, curr
),
modi = getdate( )
where exists
(
select 1
from table1 tgt
where tgt.aid = target.aid
and tgt.caseid = @caseidupd
);

insert into table1 values(caseid, aid, modi)
    select @caseidupd, source.aid, getdate()
      from
      (    
        SELECT     a.aid,a.efforts,ab.lcs
            FROM     CIP a, DC ab
            WHERE    a id = ab.id
            AND    a.id = @id
      ) source
    where not exists
    (
        select 1
        from table1 target
        where target.aid = source.aid
        and target.caseid = @caseidupd
    );

something like this...

 
INSERT (caseid,aid,modi)
 select @caseidupd,'appupdated'+source.aid,getdate()

 INSERT (caseid,aid,modi)
  select (@caseidupd,'appinserted'+source.aid,getdate()