I have two queries, one is to check the no. of times the `STUDENTNO` exists in the table `Subjects`

```
SELECT COUNT(*) AS COUNT 
FROM Subjects R  
INNER JOIN students w W ON R.studentno = W.studentno 
WHERE R.studentno = '89514'

```

Next is to get the valid `students` (whose name and student no doesn't exist in the table `SUBJECT`):

```
SELECT DISTINCT W. * 
FROM STUDENTS W 
LEFT JOIN SUBJECTS R ON W.STUDENTNO + w.NAME = R.STUDENTNO + r.NAME   
WHERE R.STUDENTNO + r.NAME IS NULL

```

I didn't get any output here. I still need to get those whose `STUDENTNO` exist in the `SUBJECT` table, but I guess this doesn't retrun it. Help. Please. Thanks