Question

I have table to test score data that I need to pivot and I am stuck on how to do it.

I have the data as this:

gradelistening speaking reading writing
0   0.0   0.0   0.0   0.0
1 399.4 423.8   0.0   0.0
2 461.6 508.4 424.2 431.5
3 501.0 525.9 492.8 491.3
4 521.9 517.4 488.7 486.7
5 555.1 581.1 547.2 538.2
6 562.7 545.5 498.2 530.2
7 560.5 525.8 545.3 562.0
8 580.9 548.7 551.4 560.3
9 602.4 550.2 586.8 564.1
10 623.4 581.1 589.9 568.5
11 633.3 578.3 598.1 568.2
12 626.0 588.8 600.5 564.8

But I need it like this:

  gr0 gr1 gr2 gr3 gr4 gr5 gr6 gr7 ...
listening 0.0 399.4 461.6 501.0 521.9 555.1 562.7 560.5 580.9...
speaking 0.0 423.8...
reading 0.0 0.0 424.2...
writing 0.0 0.0 431.5...

I don’t need to aggregate anything, just pivot the data.

Answer 1

The following is one way to solve the problem, but I am not sure if it is the most efficient.

DECLARE @PivotData table(grade int, listening float, speaking float, reading float, writing float)
INSERT into @PivotData
SELECT 0, 0.0, 0.0, 0.0, 0.0 UNION ALL
SELECT 1, 399.4, 423.8, 0.0, 0.0 UNION ALL
SELECT 2, 461.6, 508.4, 424.4, 431.5 UNION ALL
SELECT 3, 501.0, 525.9, 492.8, 491.3

SELECT TestType, [0] As gr0, [1] as gr1, [2] as gr2, [3] as gr3
FROM
(
    SELECT grade, TestType, score
    FROM 
    (
        SELECT grade, listening, speaking, reading, writing from @PivotData
    ) PivotData
    UNPIVOT
    (
        score for TestType IN (listening, speaking, reading, writing)
    ) as initialUnPivot
) as PivotSource
PIVOT 
(
    max(score) FOR grade IN ([0], [1], [2], [3])
) as PivotedData

Basically what I did was to initially unpivot the data to get a table that contains the grade, testtype, and score each in its own column, then I pivoted the data to get the answer you want. The fact that my UnPivoted source data contains the TestType column makes it so that each combination of grade and testype returns a single score, so all aggregations will just return that particular score for the combination and will not perform anything on it.

I have only done it for the first 4 grades, but I am pretty sure you can tell what you need to add to have it work for all 13 grades.