Dynamically unpivot table within Oracle - sql

Question

I have a table with several hundred columns that I need to unpivot. All of the columns that need to be unpivoted start with 'SIM_'. I know how to do this statically (example below), but I'd like a dynamic solution - as the number of columns that need be be unpivot is both long and may change over time.
SELECT
*
FROM
(SELECT
ID,
NAME,
SIM_1,
SIM_2,
SIM_3
FROM
SAMPLE_TABLE
) T UNPIVOT(SIM_RESULT FOR SIM IN (SIM_1, SIM_2, SIM_3))

Answer 1

Maybe you could (re)create a view when there is a need to refresh the list of columns. This way you will have the accurate list of columns and a way to show real data. It does the unpivoting of all columns (like SIM_%) in the time of execution.
/* sample table and data
CREATE TABLE AA_TST
(ID NUMBER(6), SIM_A VARCHAR2(20), SIM_B VARCHAR2(20), SIM_C VARCHAR2(20), SIM_D VARCHAR2(20), SIM_E VARCHAR2(20));
INSERT INTO AA_TST VALUES(1, 'A', 'B', 'C', 'D', 'E');
INSERT INTO AA_TST VALUES(2, 'AA', 'BB', 'CC', 'DD', 'EE');
INSERT INTO AA_TST VALUES(3, 'AAA', 'BBB', 'CCC', 'DDD', 'EEE');
*/
Declare
col_list VarChar2(1000);
myViewSQL VarChar2(1000);
Begin
SELECT LISTAGG(column_name, ', ') WITHIN GROUP (ORDER BY column_name)
INTO col_list
FROM all_tab_columns
WHERE table_name = 'AA_TST' And
column_name LIKE 'SIM_%';
--
myViewSQL := 'SELECT VALUE_NAME, VALUE_OF FROM AA_TST UNPIVOT (VALUE_OF FOR VALUE_NAME IN(' || col_list || '))';
execute immediate 'CREATE or replace VIEW AA_TST_VIEW AS ' || myViewSQL;
End;
/
SELECT * FROM AA_TST_VIEW;
--
-- R e s u l t
--
-- anonymous block completed
-- VALUE_NAME VALUE_OF
-- ---------- --------------------
-- SIM_A A
-- SIM_B B
-- SIM_C C
-- SIM_D D
-- SIM_E E
-- SIM_A AA
-- SIM_B BB
-- SIM_C CC
-- SIM_D DD
-- SIM_E EE
-- SIM_A AAA
-- SIM_B BBB
-- SIM_C CCC
-- SIM_D DDD
-- SIM_E EEE
--
-- 15 rows selected