Multiple row's coulmns in one row's multiple columns - sql

Question

Table Schema
ID Status Patient
1 critical Gabriel
1 moderate Frank
1 critical Dorin
2 low Peter
3 critical Noman
3 moderate Johnson
Expected OutPut
ID Patient1 Patient2
1 Gabriel Dorin
3 Noman Null
Here I have to show only those patient whose situation is critcal.
I found the similar question Multiple column values in a single row, but its in SQL also the columns are hard coded.
Thanks!

Answer 1

First step is to select the critical patients and order them:
select id, patient, row_number() over (partition by id order by patient) as rnk
from your_table
where status='critical';
After this you can select first two critical patients in this manner:
select id,
max(case when rnk=1 then patient end) as Patient1,
max(case when rnk=2 then patient end) as Patient2
from (
select id,
patient,
row_number() over (partition by id order by patient) as rnk
from your_table
where status='critical'
)
group by id;
If you want a more flexible solution you can try a query like below, but you should choose the number of ranks in before the runtime:
with your_table as
(select 1 as id, 'critical' as status, 'Gabriel' as patient from dual
union all
select 1, 'moderate', 'Frank' from dual union all
select 1, 'critical', 'Dorin' from dual union all
select 1, 'critical', 'Vasile' from dual union all
select 2, 'low', 'Peter' from dual union all
select 3, 'critical', 'Noman' from dual union all
select 3, 'moderate', 'Johnson' from dual )
select * from (
select id, patient, row_number() over (partition by id order by patient) as rnk
from your_table
where status='critical'
)
pivot (max(patient) for rnk in (1, 2, 3))
order by 1 ;
(This is for three patients.)

Answer 2

Try to build query and execute the result to a cursor.
SET SERVEROUTPUT ON
DECLARE
v_fact NUMBER := 1;
v_max_cnt number:=1;
V_query CLOB:='';
BEGIN
select max(RNum) into v_max_cnt from(
select row_number() over (partition by ID order by ID) RNum from PATIENTSTATUS where status='critical'
)x;
FOR v_counter IN 1..v_max_cnt LOOP
V_query := V_query||v_fact||' as Patient'||v_fact||(case when v_fact=v_max_cnt then '' else ',' end);
v_fact:=v_fact+1;
END LOOP;
DBMS_OUTPUT.PUT_LINE ('select * from (
select id, patient, row_number() over (partition by id order by patient) as rnk
from PATIENTSTATUS
where status=''critical'')
pivot (max(patient) for rnk in ('||V_query||'))
order by 1;');
END;
From a procedure, data can be inserted to a cursor by
OPEN CUR_Your_Cursor FOR V_query;