SQL: Creating an aggregated table from a 2-column data source - mysql

Question

I have a table within a database, and I want to aggregate the questions and answers within them into a more readable data table. The source table 👇
+-----+----------------+----------------------------+----------------+
| QID | Date Submitted | Question | Answer |
+-----+----------------+----------------------------+----------------+
| 0 | 08/04/2021 | companyName | Yaneev |
| 1 | 08/04/2021 | humanRightPolicy | George Micheal |
| 2 | 08/04/2021 | accountManagerMobileNumber | 7474236843 |
| 3 | 08/04/2021 | swiftCode | AOEU326 |
| 4 | 03/04/2021 | companyName | Eimbee |
| 5 | 03/04/2021 | humanRightPolicy | Revvie George |
| 6 | 03/04/2021 | accountManagerMobileNumber | 7475123843 |
| 7 | 03/04/2021 | swiftCode | AOEU324 |
| 8 | 04/04/2021 | companyName | Yaneev |
| 9 | 04/04/2021 | humanRightPolicy | Mark Fox |
| 10 | 04/04/2021 | accountManagerMobileNumber | 74742121231 |
| 11 | 04/04/2021 | swiftCode | 124eoKK |
+-----+----------------+----------------------------+----------------+
And what I want the 'destination' table to look like 👇
+--------------+-------------------+----------------------------+-----------+
| Company Name | humanRightsPolicy | accountManagerMobileNumber | swiftCode |
+--------------+-------------------+----------------------------+-----------+
| Yaneev | George Micheal | 7474236843 | AOEU326 |
| Eimbee | Revvie George | 7475123843 | AOEU324 |
+--------------+-------------------+----------------------------+-----------+
I'd also like to know what kind of operation this is, as I feel that it's something that isn't new in any way.

Answer 1

SQL table represent unordered sets. Let me assume that you have an ordering column. With such a column, you can assign a group to each set of rows for the same company and then use conditional aggregation:
select max(case when question = 'Company Name' then answer end) as company_name,
max(case when question = 'Q1' then answer end) as q1,
max(case when question = 'Q2' then answer end) as q2,
max(case when question = 'Q3' then answer end) as q3
from (select t.*,
sum(case when question = 'Company Name' then 1 else 0 end) over (order by <ordering col>) as grp
from t
) t
group by grp;
Note that this answers the question that you asked, where all the questions are known -- so the result columns are all known. If you don't know the questions in advance, you need to use dynamic SQL (i.e. construct the query as a string and then execute it). How to do that depends entirely on the database you are using.
EDIT:
In older versions of MySQL, you can use a subquery:
select max(case when question = 'Company Name' then answer end) as company_name,
max(case when question = 'Q1' then answer end) as q1,
max(case when question = 'Q2' then answer end) as q2,
max(case when question = 'Q3' then answer end) as q3
from (select t.*,
(select count(*)
from t t2
where t2.question = 'Company Name' and
t2.<ordering col> <= t.<ordering col>
) as grp
from t
) t
group by grp;