Second level lookup with SQL statement - sql-server

Question

How do I write a SQL statement that does a second level lookup only if first is not matched. For example:
In the below query, if my SEDOLCode condition does not return a record, proceed to lookup with condition 2 with RICCode.
select
*, GETDATE()
from
Securities sec
where
sec.SEDOLCode = 'ABCDEF'
or sec.RICCode = '002815.SZ'
This query is returning two different records - for example:
1234 ABCDEF DUMY906.X
5675 EFTFS 002815.SZ
I am taking data from a file to update the Pricetable as below. I want to use SedolCode as primary lookup.
IF ##ROWCOUNT = 0
INSERT INTO dbo.Price (sec.SecurityID, ClosingPrice, UpdatedDate, UpdatedByUser, Priced)
SELECT
..., GETDATE()
FROM
Securities sec
WHERE
sec.SEDOLCode = #SedolCode
OR sec.RICCode = #RicCode

Answer 1

Try this the logic is basically if the sedolcode is found then it will only meet the first condition. Otherwise the count of that sedolcolde will be 0 and it will look at riccode.
select
*, GETDATE()
from
Securities sec
where
sec.sedolcode = 'ABCDEF'
OR ((SELECT COUNT(1) FROM securites WHERE sedolcode ='ABCDEF') = 0 AND sec.riccode = '002815.SZ')

Answer 2

Ah - reminds me of my FTSE days........
Match Sedol and Not Ric
or
Ric and Not Sedol and use myOrdering & TOP to get the first.
INSERT INTO dbo.Price
(
sec.SecurityID
, ClosingPrice
, UpdatedDate
, UpdatedByUser
, Priced
)
SELECT TOP 1 [specifiy fields to insert]
FROM
(
select 1 as myOrdering ...
, GETDATE()
from Securities sec
WHERE
(sec.RICCode = #RicCode AND sec.SEDOLCode != #SedolCode)
UNION
select 2 as myOrdering ...
, GETDATE()
from Securities sec
WHERE
(sec.RICCode = #RicCode AND sec.SEDOLCode != #SedolCode)
)SUB_Q ORDER BY myOrdering