update query with insertion?

i need a query which have to do both update and insert..

first i have to check this condition

 SELECT TOP 1 * FROM NEC_Customer_DB_Map where DB_AvailabilityFlag = 'Y'

and if DB_AvailabilityF开发者_Go百科lag = 'Y' i have to update this 'Y' as 'ASSIGNED' and also i have to insert by using

 INSERT INTO NEC_Customer_DB_Map(NEC_CustomerCode,NEC_CustomerName) VALUES(@NEC_CustomerCode,@NEC_CustomerName)

can anyone combine these into one query..Any Suggestion?

Since your question is tagged with sql-server-2008 you could consider usinge the MERGE-statement:

http://technet.microsoft.com/en-us/library/bb510625.aspx

You could use a where clause to make the insert conditional:

INSERT INTO NEC_Customer_DB_Map(NEC_CustomerCode,NEC_CustomerName) 
SELECT @NEC_CustomerCode,@NEC_CustomerName
WHERE EXISTS (SELECT * FROM NEC_Customer_DB_Map where DB_AvailabilityFlag = 'Y')