how to implementt his query in Condtional Spilit for Table except with merge join

Hi all!

Happy New Year!!!!

here looking for insert and update with difference in two tables.  Depends upon on the value of the source and destination table, update statement should execute.

For example 

[ Dest Table logistic in ('SB','TR') and Src Table b.logistic in ('SC','','RC','RB') ]OR [ Dest Table logistic in ('SB','TR') and Src Table b.logistic in ('SC','','RC','RB') ] then update Src valueb.logistic otherwise retain dest value.

Sample Script

updateDest_tab Logistic= case
               whena.logistic in ('SB','TR') and b.logistic in ('SC','','RC','RB') then b.logistic
               when isnull(a.logistic,'')=''  andb.logistic in ('RB','SC') then b.logistic
              else a.logistic end

Location= case                                  
                when a.logistic in ('SB','TR') and b.logistic in ('SC','','RC','RB') then b.Location                                         
                when isnull(a.logistic,'')=''  and b.logistic in ('RB','SC') then b.Location  else a.Location end,             
SentBy =  case                                  
             when a.logistic in ('SB','TR') and b.logistic in ('SC','','RC','RB') then b.SentBy                                         
                when isnull(a.logistic,'')=''  and b.logistic in ('RB','SC') then b.SentBy                                 
           else  a.sentby end,                                   
SentTo = case                                   
                when a.logistic in ('SB','TR') and b.logistic in ('SC','','RC','RB') then b.SentTo                                         
                when isnull(a.logistic,'')=''  and b.logistic in ('RB','SC') then b.SentTo                                 
            else  a.SentTo end, fromDest_tab a join Src_tab b a.pk_id=b.pk_id

......

my Data flow Task is

1.two OLE DB Sources

2.Mege Join (PK_ID -join key)

3.Conditional spilit

   a.Insert case - isnull(DstPK_ID)

   b.Update case -?

4.OLE DB Destination for insert and OLE DB Command for update.

now need guide for Update case expression. and any good method to implement this..

Thanks regards with

T KUMAR