Finding your left and right neighboring rows using a temp table

/* declare variables */
DECLARE @userID INT
DECLARE @maxCnt INT
DECLARE @tmpUser TABLE (tmpId INT IDENTITY(0,1), UserID INT)

/* quick way to limit to one user */
SET @userID = 223

/* populate the temp table */
INSERT INTO @tmpUser (UserId)
   SELECT UserId FROM users

/* find max value for modulo math */
SELECT @maxCnt = COUNT(userid) FROM @tmpUser

--select * from @tmpUser

/* join against orginal data, using mod math and tmp table */

SELECT u.UserId, l.UserId, r.UserId 
  FROM users AS us
  left join @tmpUser AS u ON u.userid = us.userid 
  left join @tmpUser AS l ON ((u.tmpId - 1 + @maxCnt) % @maxCnt) = l.tmpId
  left join @tmpUser AS r ON ((u.tmpId + 1)% @maxCnt) = r.tmpId
  WHERE us.userID = @UserID