问sqlquery找不到

EN

DECLARE @SemesterId INT
       ,@ExamYearId INT

SET @SemesterId = 3;
SET @ExamYearId = 3;

SELECT * 
FROM TableName t
WHERE EXISTS (SELECT 1 
              FROM TableName 
              WHERE SemesterId  = @SemesterId - 1
               AND  ExamYearId  = @ExamYearId - 1
               AND  t.StudentId = StudentId   )
AND NOT EXISTS (SELECT 1 
              FROM TableName 
              WHERE SemesterId  = @SemesterId 
               AND  ExamYearId  = @ExamYearId 
               AND  t.StudentId = StudentId   )  

SELECT st1.*
  FROM Student st1 
  left join Student st2 
    on st1.id = st2.id 
   and st1.Semesterid=2 
   and st2.Semesterid=3 
   and st2.Examyearid=3 
 where st2.id is null