Check existence of a database

CREATE procedure usp_checkdb (@dbname nvarchar(128))
as
begin
/* Check, How to Run:

EXEC usp_checkdb @dbname = 'Enter DB'

*/
IF (EXISTS (SELECT name FROM master.dbo.sysdatabases 
WHERE ('[' + name + ']' = @dbname 
OR name = @dbname)))

SELECT 'YES'


IF (NOT EXISTS (SELECT name FROM master.dbo.sysdatabases 
WHERE ('[' + name + ']' = @dbname 
OR name = @dbname)))

SELECT 'No'
END