Here's the deal...
Instead of architecting and loading a table like...
create teble foo (col1 text, col2 text, col3 text, col4 text, col5 text);
insert into foo (col1,col2,col3,col4,col5) values ('c1',null,'c3','c4',null);
They did this instead...
create table foo (property text, value text);
insert into foo (property, value) values ('col1','c1'), ('col3','c3'), ('col4','c4');
Notice how "col2" and "col5" were simply left out of the table in the 2nd model to indicate null.
The question is how to do this model 1 query for model 2...
select col1,col2 from foo where col4='c4' and col5 <> 'xxx';
I know I have to use outer joins to deal with the potential of nulls. But I don't know how to construct this. I won't list my failed attempts (so as not to embarass myself :-))
Thanks in Advance !
