How to avoid displaying empty rows in a table?

Question

The situation is as follows:
I have got a set of questions under a particular category say marketing category.
The user will be displayed with a table consisting of a set of questions from a particular category with four radio buttons for each question.
Now once he is done with all the set of questions under a particular category, he will be navigated to the next set of questions under some other category say 'xyz'
Now instead of creating seperate view objects for each category, we have created a view object which will hold all the set of questions from all the category but will display only the set of questions under a particular category by declaring a variable in the backing bean and setting the question rendering to the value in the variable. the value to the variable will be changed once the user is done with answering all the set of questions under a particular category.
Now the problem that i am facing is:
Because of the rendering condition that i have used, it displays only those rows that have the rendering condition set to the variable in the backing and displays all other empty rows overlapped.
How do i avoid this situation ??

Answer 1

Seems odd, but you could use COALESCE to achieve this.
ME_XE?create table all_nullz (col1 number, col2 number, col3 number);
Table created.
Elapsed: 00:00:00.20
ME_XE?
ME_XE?insert into all_nullz values (1,2,3);
1 row created.
Elapsed: 00:00:00.12
ME_XE?insert into all_nullz values (null, null, null);
1 row created.
Elapsed: 00:00:00.06
ME_XE?
ME_XE?delete from all_nullz where coalesce(col1,col2,col3) is null;
1 row deleted.
Elapsed: 00:00:00.26
ME_XE?