Case statement-How to achieve the target format in MYSQL? - mysql

Question

My source data looks something like this:
enter image description here
Now, for every distinct PK, I want to extract only data related to Z99 code, which has closest date with either Z10 or Z39 Codes and additionally calculate the difference of the z99 and z10/39 date too.
Expected result:enter image description here
Can someone guide me on how to achieve this using case statement or any other better way?
Thanks.

Answer 1

I tried the below code and it worked for me.
Note:
I have created intermediate tables to get the results. If you don't have permission, you can go ahead with creating temptable or CTE
If diff is same for z39 and z10, then both will be taken as you did not specify any priority
/* tbl refers to your input table */
/* daten refers to date */
create table ads as
select
a.daten,
b.daten as z99_dt,
a.pk, a.code as codea,
b.code as codeb,
(a.daten - b.daten) as diff
from tbl as a
inner join (select distinct code, pk, daten
from tbl
where code='z99') as b
on a.code<>b.code and a.pk = b.pk
where codea IN ('z39', 'z10');
In the above snippet, an ads would be created with necessary calculations.
Following snippet will find minimum of diff
create table ref as
select pk, min(diff) as min_diff
from ads
group by pk;
Following snippet joins ref table and ads table to get the final result
select a.pk, codea as st_code, daten as st_dt, codeb as end_code, z99_dt as end_dt, diff from ads as a
inner join ref as b
on a.pk=b.pk and a.diff=b.min_diff;
Please try this out and let me know if this works!