Constrain SQL like pattern for Commission Rate lookup

 SQL Like allow pattern match but normally return multiple rows. If you have one 
commision rate for a pattern, carefully specified pattern will allow look up to 
return just one value without the ambiguity as shown here:
  FSMI% vs. FSMIU%

In general, we need to consider the following:

(1) Clearly define Bloomberg symbol as 2 charaters key and Add GMO prefix to 
generate external security id pattern. (GMO_EXT_SEC_ID_PATN_DEF).
    In particular, Commission Rate table GMO_BROKER_COMM need to have Foreign key 
constraints from GMO_EXT_SEC_ID_PATN_DEF to avoid invalid security.

(2) GMO_BROKER_COMM need to have a trigger constraint to make sure the following
 will not return more than one row:
   select * from GMO_BROKER_COMM2 where 
     (EXT_SEC_ID_PATN like @EXT_SEC_ID_PATN or
           @EXT_SEC_ID_PATN like EXT_SEC_ID_PATN)

in particular, if we need to have both FSMI% and FSMIU%, we will need to span out
even with duplcation rates:
       FSMIH%   2.95
       FSMIG%   2.95
       FSMIZ%   2.95

       FSMIU%   4.95
 
This will eliminate ambiguity.

(3) We need [BB_SYMBOL] [char](2) NOT NULL to keep space for Bloomberg symbol
    and that will avoid some ambiguity like FBC % vs. FBCC%

(4) FBC % vs. FBC%
    FB C  -- SET50 FUTURES  maps to FBC %
    F  BC -- CORN FUTURE    maps to FBC% 
    we currenlty do not have commission rate for FBC %. But we need to be 
    careful when enter rates in the future

(5) The following is the SQL used in Mid-Tier:
    select * from GMO_BROKER_COMM where @ext_sec_id like EXT_SEC_ID_PATN