SQLPlus Pivot Date Column - sql

Question

I have a query where I need to pivot a field that includes multiple dates. In short, the administereddate column needs to be pivoted to 6 columns with the dates from newest to oldest across the row.
My current effort is as follows
SELECT student_number,
wheninput,
whoinput,
certificatetype,
MAX(CASE
WHEN vaccine_name = 'DTP' THEN
TO_CHAR(administereddate, 'mm/dd/yyyy')
ELSE
''
END) AS "DTP"
FROM
(
SELECT TO_CHAR(administeredDate, 'mm/dd/yyyy') dose_date,
ROW_NUMBER() OVER (PARTITION BY vaccine_name ORDER BY administereddate DESC) dose
FROM ps.pshealthgrade1)
PIVOT(
LISTAGG(dose_date) WITHIN GROUP (ORDER BY dose_date DESC)
FOR dose IN (1 DTP_dose1,
2 DTP_dose2,
3 DTP_dose3,
4 DTP_dose4,
5 DTP_dose5,
6 DTP_dose6)
)
)
WHERE vaccine_name = 'DTP'
GROUP BY student_number,
wheninput,
whoinput,
vaccine_name,
administereddate,
certificatetype
ORDER BY student_number, vaccine_name, administereddate;

Answer 1

You need dynamically detecting the latest six vaccine dates probably to be counted per each day. In order to accomplish this, create such a function firstly ;
CREATE OR REPLACE FUNCTION get_vaccine_rs(
i_vcc ps.pshealthgrade1.vaccine_name%TYPE
) RETURN SYS_REFCURSOR IS
v_recordset SYS_REFCURSOR;
v_sql VARCHAR2(32767);
v_str VARCHAR2(32767);
BEGIN
SELECT LISTAGG( ''''||TO_CHAR(administeredDate, 'mm/dd/yyyy')||''' AS "DTP_dose'||rn||'"' , ',' )
WITHIN GROUP ( ORDER BY rn )
INTO v_str
FROM ( SELECT *
FROM
( SELECT administeredDate, ROW_NUMBER() OVER (ORDER BY administeredDate DESC) AS rn
FROM ( SELECT DISTINCT administeredDate
FROM ps.pshealthgrade1
WHERE vaccine_name = i_vcc )
)
WHERE rn <= 6 );
v_sql :=
'SELECT *
FROM ps.pshealthgrade1
PIVOT
(
COUNT(*) FOR administeredDate IN ( '|| v_str ||' )
)
';
OPEN v_recordset FOR v_sql USING i_vcc;
RETURN v_recordset;
END;
/
Then run the below code :
VAR rc REFCURSOR
EXEC :rc := get_vaccine_rs('DTP');
PRINT rc
from SQL Developer's Command Line in order to see the result set.