Waterfall Logic for SQL Server Columns - sql

Question

Can you please help me with the following.
I have the data with flags as the following and i need to add 5 additional columns based on those flag columns in a waterfall/Cascade way. I tried to accomplish this with case statement but the logic is becoming more confusing.
Here is the sample data and how the end result should look like.
DECLARE #T AS TABLE
(
ID INT,
Mortality VARCHAR(10),
Readmission varchar(10),
EDVisit varchar(10),
Return_to_OR varchar(10),
Sepsis varchar(10)
);
DECLARE #endresult AS TABLE
(
ID INT,
Mortality VARCHAR(10),
Readmission varchar(10),
EDVisit varchar(10),
Return_to_OR varchar(10),
Sepsis varchar(10),
Indicator1 varchar(15),
Indicator2 varchar(15),
Indicator3 varchar(15),
Indicator4 varchar(15),
Indicator5 varchar(15)
);
insert into #T VALUES
(1,'Y', 'N', 'Y','Y','Y'),
(2,'N','Y','N','Y','Y'),
(3,'N','N','N','Y','Y')
insert into #endresult VALUES
(1,'Y', 'N', 'Y','Y','Y','Mortality','EDVisit','Return_to_OR','Sepsis',null),
(2,'N','Y','N','Y','Y','Readmission','Return_to_OR','Sepsis',null,null),
(3,'N','N','N','Y','Y','Return_to_OR','Sepsis',null,null,null)
select * from #T
select * from #endresult

Answer 1

Here's an option which uses a bit of JSON in concert with a conditional aggregation.
On a side note: Assuming you had a typo EDVisit vs ERVisit
Example or dbFiddle
select A.*
,B.*
From #T A
Cross Apply (
Select Indicator1 = max(case when Seq=1 then [Key] end)
,Indicator2 = max(case when Seq=2 then [Key] end)
,Indicator3 = max(case when Seq=3 then [Key] end)
,Indicator4 = max(case when Seq=4 then [Key] end)
,Indicator5 = max(case when Seq=5 then [Key] end)
From (
Select [Key]
,Value
,Seq = row_number() over (order by (select null))
From OpenJson((Select A.* For JSON Path,Without_Array_Wrapper ))
Where [Key] not in ('ID')
and Value<>'N'
) B1
) B
Returns