The teacher wants math scores as letters: 'A' for 90 and up, 'B' for 75 and up, 'C' for 60 and up, 'D' for the rest. From scores, pick the math rows (subject is 'math') with three columns: student_id, score and the letter.
The tables
students
id
name
class
age
city
1
Amy
1A
12
Leeds
2
Ben
1A
13
York
3
Cara
1B
12
NULL
4
Dan
1B
14
Leeds
5
Eva
1A
12
Hull
6
Finn
1C
13
NULL
7
Gus
1C
12
York
7 rows
scores
id
student_id
subject
score
1
1
math
92
2
1
art
78
3
2
math
65
4
2
art
88
5
3
math
74
6
4
math
55
7
4
art
90
8
5
math
81
9
5
art
NULL
10
7
math
99
10 rows
students
id
name
class
age
city
1
Amy
1A
12
Leeds
2
Ben
1A
13
York
3
Cara
1B
12
NULL
4
Dan
1B
14
Leeds
5
Eva
1A
12
Hull
6
Finn
1C
13
NULL
7
Gus
1C
12
York
7 rows
scores
id
student_id
subject
score
1
1
math
92
2
1
art
78
3
2
math
65
4
2
art
88
5
3
math
74
6
4
math
55
7
4
art
90
8
5
math
81
9
5
art
NULL
10
7
math
99
10 rows
query.sql
SELECT student_id, score,
CASE
-- your code here: three WHENs from high to low (90, 75, 60), then ELSE 'D'
END
FROM scores
WHERE subject = 'math';
Ctrl + Enter runs too
Result
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