mysql sub query for find grade - mysql

Question

I have tabel like this
+----+-------+------------+-------+
| No | NIK | Nama | Nilai |
+----+-------+------------+-------+
| 1 | 06001 | Syafruddin | 70 |
| 2 | 20000 | Maman | 90 |
| 3 | 30000 | Linda | 40 |
| 4 | 40000 | Tesa | 71 |
+----+-------+------------+-------+
+-------------+-------+------------------+
| Range_Nilai | Point | Keterangan |
+-------------+-------+------------------+
| 0 s/d 50 | E | Tidak Lulus |
| 51 s/d 80 | C | Cukup |
| 81 s/d 100 | A | Sangat Memuaskan |
+-------------+-------+------------------+
and I want to get my results like this
but my results like this
when I try to change my query like this
THEN (SELECT b.Point,b.Keterangan FROM range_nilai b where b.Range_Nilai='0 s/d 50')
I got error 'Operand should contain 1 column(s)'
can someone help me pls?
this my fiddle
SELECT a.*,
( CASE
WHEN a.nilai >=0 && a.Nilai<=50
THEN (SELECT Point FROM range_nilai where Range_Nilai='0 s/d 50')
WHEN a.nilai >50 && a.Nilai<=80
THEN (SELECT Point FROM range_nilai where Range_Nilai='51 s/d 80')
WHEN a.nilai >80 && a.Nilai<=100
THEN (SELECT Point FROM range_nilai where Range_Nilai='81 s/d 100')
ELSE NULL
END
) as Point,
( CASE
WHEN a.nilai >=0 && a.Nilai<=50
THEN (SELECT Keterangan FROM range_nilai where Range_Nilai='0 s/d 50')
WHEN a.nilai >50 && a.Nilai<=80
THEN (SELECT Keterangan FROM range_nilai where Range_Nilai='51 s/d 80')
WHEN a.nilai >80 && a.Nilai<=100
THEN (SELECT Keterangan FROM range_nilai where Range_Nilai='81 s/d 100')
ELSE NULL
END
) as Keterangan
FROM nilai a
this my last query I have.
may someone have more better query than me?

Answer 1

You can join the tables and use the function SUBSTRING_INDEX() in the ON clause:
select n.*, r.Point, r.Keterangan
from nilai n inner join range_nilai r
on n.Nilai
between
substring_index(r.Range_Nilai, ' s/d ', 1)
and
substring_index(r.Range_Nilai, ' s/d ', -1)
See the demo.
Results:
| No | NIK | Nama | Nilai | Point | Keterangan |
| --- | ----- | ---------- | ----- | ----- | ---------------- |
| 1 | 6001 | Syafruddin | 70 | C | Cukup |
| 2 | 20000 | Maman | 90 | A | Sangat Memuaskan |
| 3 | 30000 | Linda | 40 | E | Tidak Lulus |
| 4 | 40000 | Tesa | 71 | C | Cukup |