Null Replacement in Oracle Pivot Table - oracle

Question

I am currently using the following code to pivot a table and it works perfectly. Now I want to replace any null values with 'No Data' after it is summed but I am getting errors, so I think I am placing the case statement in the wrong place.
This works:
SELECT *
FROM (SELECT PROV_NO, DATA_YEAR, DATA_MONTH, MEASURE_ID, CASES
FROM pivot_test_2)
PIVOT (SUM(CASES) FOR (MEASURE_ID) IN ('MORT_30_AMI', 'MORT_30_HF', 'MORT_30_PN'))
order by PROV_NO, DATA_YEAR, DATA_MONTH;
but this does not
SELECT *
FROM (SELECT PROV_NO, DATA_YEAR, DATA_MONTH, MEASURE_ID, CASES
FROM pivot_test_2)
PIVOT (SUM(CASES) FOR (MEASURE_ID) IN ('MORT_30_AMI', 'MORT_30_HF', 'MORT_30_PN'))
case when MORT_30_HF is null then 'No Data' else MORT_30_HF end
order by PROV_NO, DATA_YEAR, DATA_MONTH;
I get "ORA-00933: SQL command not properly ended" as the error. I'm trying to place ";" around but the error is still the same. I am currently in Oracle 11g and using Golden as my scripting/retrieval software.

Answer 1

You can move the CASE statement to the SELECT statement and handle the NULL values there. Better yet, use COALESCE. But unfortunately you have to do this for each item in the SELECT list:
SELECT
--Must manually reference each column.
COALESCE(TO_CHAR(MORT_30_AMI), 'No Data') MORT_30_AMI,
COALESCE(TO_CHAR(MORT_30_HF), 'No Data') MORT_30_HF,
COALESCE(TO_CHAR(MORT_30_PN), 'No Data') MORT_30_PN,
PROV_NO, DATA_YEAR, DATA_MONTH
FROM (SELECT PROV_NO, DATA_YEAR, DATA_MONTH, MEASURE_ID, CASES
FROM pivot_test_2)
PIVOT
(
SUM(CASES)
FOR (MEASURE_ID) IN
--Use aliases to make the columns easier to use.
('MORT_30_AMI' MORT_30_AMI, 'MORT_30_HF' MORT_30_HF, 'MORT_30_PN' MORT_30_PN))
ORDER BY PROV_NO, DATA_YEAR, DATA_MONTH;
A Simpler Version That Doesn't Work
Ideally you would be able to replace this part of the code:
SUM(CASES)
With this:
COALESCE(TO_CHAR(SUM(CASES)), 'No data')
Then you wouldn't need to handle each column separately. But there doesn't appear to be a way to automatically apply a non-aggregate function to the results of a PIVOT. Using the above code generates this error message:
ORA-56902: expect aggregate function inside pivot operation
Sample Schema
create table pivot_test_2
(
PROV_NO CHAR(6),
DATA_YEAR NUMBER(4),
DATA_MONTH Number(2),
MEASURE_ID VARCHAR2(250),
CASES NUMBER
);
insert into pivot_test_2
select 'A', 2000, 1, 'MORT_30_AMI', 1 from dual union all
select 'A', 2000, 1, 'MORT_30_AMI', 1 from dual union all
select 'A', 2000, 1, 'MORT_30_HF', 2 from dual union all
select 'A', 2000, 1, 'MORT_30_HF', 2 from dual;

Answer 2

Thanks everyone, with help from you all, I was able to cob this together and it works.
SELECT PROV_NO, DATA_YEAR, DATA_MONTH,
case when MORT_30_AMI is null then 'No Data' else to_char(MORT_30_AMI) end as MORT_30_AMI,
case when MORT_30_HF is null then 'No Data' else to_char(MORT_30_HF) end as MORT_30_HF,
case when MORT_30_PN is null then 'No Data' else to_char(MORT_30_PN) end as MORT_30_PN
FROM pivot_test_2
PIVOT (SUM(CASES) FOR (MEASURE_ID) IN ('MORT_30_AMI' as MORT_30_AMI,'MORT_30_HF' as MORT_30_HF, 'MORT_30_PN' as MORT_30_PN))
order by PROV_NO, DATA_YEAR, DATA_MONTH;

Answer 3

Use DECODE keyword for the query defined fields (from the list of pivot defined fields) and then replace NULL with whatever value you need. i.e., instead of NULL replace it with 'No Data'. I believe that should solve this issue.