TSQL - create columns based on field values and duplicate rows - sql

Question

in tsql how can I turn this sample table:
ID FIELDNO ROWNO VALUE
ABC 2 1 Cat1Val1
ABC 2 2 Cat1Val2
ABC 2 3 Cat1Val3
ABC 3 1 Cat2Val1
ABC 3 2 Cat2Val2
ABC 5 1 Cat3Val1
to a table that will create three columns based on the fieldno and duplicate the rows so that it lists all possible variations of whatever fieldno has the highest rowNo?
So fieldno 2 will become CAT1, 3 -> CAT2 and 5 -> CAT3
Expected result:
ID CAT1 CAT2 CAT3
ABC Cat1Val1 Cat2Val1 Cat3Val1
ABC Cat1Val1 Cat2Val2 Cat3Val1
ABC Cat1Val2 Cat2Val1 Cat3Val1
ABC Cat1Val2 Cat2Val2 Cat3Val1
ABC Cat1Val3 Cat2Val1 Cat3Val1
ABC Cat1Val3 Cat2Val2 Cat3Val1
I could then use this as a base to join with other tables.
Here's a fiddle with more data.
I've tried to create some CASE WHEN clauses but I think this is not going to work.
Hope you can show me a way how this can be solved.
Thank you.

Answer 1

This seems a bit unorthodox, but this should do it for you if I understood the problem correctly:
SELECT d1.id, d1.value Cat1, d2.value Cat2, d3.value Cat3
FROM Docs d1
INNER JOIN Docs d2 ON d2.id = d1.id AND d2.rowNo = d1.rowNo AND d2.fieldNo = 3
INNER JOIN Docs d3 ON d3.id = d2.id AND d3.rowNo = d1.rowNo AND d3.fieldNo = 5
AND d1.fieldNo = 2
This solution of course expects values will exist for each column.
Revised answer...
If the third join and only the third join (Docs.fieldNo = 5) is optional, you can do something like this:
SELECT
d2.id,
d2.value Cat1,
d3.value Cat2,
d5.value Cat3
FROM
(SELECT 2 fieldNo2, 3 fieldNo3, 5 fieldNo5) f
INNER JOIN Docs d2 ON d2.fieldNo = f.fieldNo2
INNER JOIN Docs d3 ON d3.fieldNo = f.fieldNo3 and d3.rowNo = d2.rowNo and d3.id = d2.id
LEFT JOIN Docs d5 ON d5.fieldNo = f.fieldNo5 and d5.rowNo = d2.rowNo and d5.id = d2.id
I've revised the rest of the query so that hopefully what it's doing is a little clearer.
Here are some answers on joins which you may find helpful: What is the difference between "INNER JOIN" and "OUTER JOIN"?

Answer 2

I have tried this in an access database:
replace myvalue with value (value is a reserved word in access)
I called the table test so replace it with your tablename.
SELECT test.id, test.myValue AS cat1, test_1.[myValue] AS cat2, test_2.myValue AS cat3
FROM test, test AS test_1, test AS test_2
WHERE (((test.myValue) Like "cat1*")
AND ((test_1.[myValue]) Like "cat2*")
AND ((test_2.myValue) Like "cat3*"))
ORDER BY test.myValue, test_1.[myValue], test_2.myValue;