What do you mean by not functional?

I am not sure you need the temp tables. Does this help?

IF (@TC = 'BUY')

BEGIN

UPDATE....WHERE A.TransType = 'BUY'

END

IF (@TC = 'SELL')

BEGIN

UPDATE....WHERE A.TransType = 'SELL'

END

IF (@TC = 'ALL')

BEGIN

UPDATE....WHERE A.TransType IN ('BUY','SELL')

END

Before you start updating data please test with SELECT statements first to validate.