Show column names of the table in 1st data row of the query output dynamically in Oracle

Question

There is one table, let us say VW_RESULT like below:

ID Quarter Risk
00001 Q0 2
00001 Q1 3
00001 Q2 1
00001 Q3 1
00001 Q4 2

Now I have to show the column names in the 1st row.

I want output like this:

Col1 Col2 Col3
ID Quarter Risk
00001 Q0 2
00001 Q1 3
00001 Q2 1
00001 Q3 1
00001 Q4 2

I can easily achieve this if the number of columns is fixed, using UNION ALL .

But the number of columns will vary from time to time.

I want to make this dynamic so that I don't have to put column names manually.

I am using Oracle 11g .

Answer 1

Take your columns in variable and concatenate all columns you are getting at every run..execute your with execute immediate and concatenate your variable with the statement as well

Answer 2

To achieve your requirement, all your datatype should be string as all the columns are strings. In case if any of your datatype is other than string it will not work. Eg: ID column seems to be integer datatype, if you are trying to merge 'ID' string into ID column, according to SQL standard, it will fail. However below is the solution if all the columns in the respective table is in string format.

declare 

v_Sql1 varchar(1000);
v_Sql2 varchar(1000);

begin

select  (LISTAGG(chr(39)||column_name||chr(39), ',') WITHIN GROUP (ORDER BY 
column_id)) into v_Sql1 from cols where table_name = 'VW_RESULT'; 

v_Sql2:= 'select * from
(select  column_name from cols where table_name = ''VW_RESULT'') 
pivot
(
max(column_name)
for column_name in (' || v_Sql1 || '))
union select * from VW_RESULT'; 

dbms_output.put_line(v_Sql1);
dbms_output.put_line(v_Sql2);

execute immediate v_Sql2;

end;
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