Get result using two tables without using any loop - sql

Question

I have two tables Temp_Test and Temp_Marks.
Temp_Test is having following columns
id UserId QId QTitle QMarks
1 A1 1 A 5
2 A1 2 B 6
3 A1 3 C 4
4 A1 4 D 5
5 B3 1 A 8
6 B3 2 B 6
7 B3 3 C 4
8 B3 4 D 3
9 Z9 1 A 2
10 Z9 2 B 7
11 Z9 3 C 9
12 Z9 4 D 3
and Temp_Marks has following Columns
Id Score A B C D
1 1 10 5 40 12
2 2 20 10 50 23
3 3 30 15 60 34
4 4 40 20 70 54
5 5 50 25 80 84
6 6 60 30 90 36
7 7 70 35 10 85
8 8 80 40 20 97
9 9 90 45 30 58
10 10 100 50 100 48
I want to fetch result of particular UserId.
eg. If for A1, QTitle is A and marks is 5 in Temp_test table then fetch record from Column A where Score is 5 from Temp_Marks table.
without using while loop want to fetch all records of particular UserId or UserIds.
Can anyone help on this?

Answer 1

You may want to UNPIVOT the Temp_Marks first to easily join it with Temp_Test, and then PIVOT the result to achieve the desired format:
;WITH CteUnpivotedMarks AS(
SELECT
ID, Score, Col = 'A', Value = A
FROM Temp_Marks
UNION ALL
SELECT
ID, Score, Col = 'B', Value = B
FROM Temp_Marks
UNION ALL
SELECT
ID, Score, Col = 'C', Value = C
FROM Temp_Marks
UNION ALL
SELECT
ID, Score, Col = 'D', Value = D
FROM Temp_Marks
)
SELECT
UserId = t.UserID,
A = MAX(CASE WHEN t.QTitle = 'A' THEN c.Value END),
B = MAX(CASE WHEN t.QTitle = 'B' THEN c.Value END),
C = MAX(CASE WHEN t.QTitle = 'C' THEN c.Value END),
D = MAX(CASE WHEN t.QTitle = 'D' THEN c.Value END)
FROM Temp_Test t
INNER JOIN CteUnpivotedMarks c
ON t.QTitle = c.Col
AND t.QMarks = c.Score
GROUP BY t.UserID
RESULT
UserId A B C D
---------- ----------- ----------- ----------- -----------
A1 50 30 70 84
B3 80 30 70 34
Z9 20 35 30 34