How to show time cost for one query in T-SQL?

      DECLARE @starttime DATETIME2 = SYSDATETIME(), @alltime datetime2 = sysdatetime();

      DECLARE @finishtime INT;

/* Your query is in here */

      SELECT @finishtime = DATEDIFF(millisecond, @starttime, SYSDATETIME());

      PRINT '(ms): ' + CONVERT(VARCHAR, @finishtime)