APEX

Hello All,

I am getting this ora 20999 error when i execute the below code .

• ORA-20999: Parsing returned query results in "ORA-20999: Failed to parse SQL query! ORA-06550: line 4, column 24: ORA-00936: missing expression".

declare
l_sql varchar2(32700);
group_col varchar2(3000);
begin 
for c1 in(
  select
    t1.column_name
  , t2.column_value
  from ALL_TAB_COLS t1
  left join table( apex_string.split( :P3_COLUMNS, ':' ) ) t2 on t1.column_name = t2.column_value
  where 1 = 1
    and owner='KK' and table_name='PWP_DEMOG'
) loop
  l_sql := l_sql || ',' || case when c1.column_value is not null then c1.column_name else 'null ' || c1.column_name end;
end loop;
select replace(:P3_COLUMNS,':',',') into group_col from dual;
l_sql := 'select distinct ' || ltrim( l_sql, ',' )  || ',count(distinct studyid) over (partition by '|| rtrim(group_col,',') ||') cnt '||
          ' 
          from kk.pwp_demog'  
          ;
          
           return l_sql;

This executes fine when i print the same in Text area with PL/SQL Function body as source.

select distinct DEM_RACE_ETHNICITY,CLINICAL_STAGE_AJCC,null CLINICAL_HER2,count(distinct studyid) over (partition by DEM_RACE_ETHNICITY,CLINICAL_STAGE_AJCC) cnt  
          from kk.pwp_demog

Can anyone please help me on identifying what is going wrong here.

Thanks!