unique pair of columns

[lgaorcl]

Hi, I need to create a view for three columns a, b, c from a table. The pair of b, c needs to be unique. Is there a good way I can do this?

Thank you very much for the help!

[DaPi]

I can think of three different ways of interpreting your question . . . I suggest you give us an example of the data in the table and what you want to see in the view.

[lgaorcl]

The table has three columns for example, label, sid, s_size.

The view wants these three columns with unique combination of sid and s_size.

Thanks!

[gandolf989]

Originally posted by lgaorcl
The table has three columns for example, label, sid, s_size.

The view wants these three columns with unique combination of sid and s_size.

Thanks!

Why don't you just do this?

SELECT DISTINCT label, sid, s_size
  FROM the_table;

[lgaorcl]

Does the statement: select distinct label, sid, s_size from the_table;
return distinct combination of label, sid, s_size or just distinct label with sid, s_size?

[DaPi]

Or is it

SELECT label, sid, s_size
  FROM the_table
WHERE (sid, s_size) IN
(select sid, s_size
 from the_table
 group by sid, s_size
 having count(*) = 1);

or perhaps

select MAX(label), sid, s_size
 from the_table
 group by sid, s_size

[DaPi]

Originally posted by lgaorcl
Does the statement: select distinct label, sid, s_size from the_table;
return distinct combination of label, sid, s_size or just distinct label with sid, s_size?

I think you are in the perfect position to find out . . . by trying it.


P.S. I still haven't a clue as to what you want.

[srt]

Does the statement: select distinct label, sid, s_size from the_table;
return distinct combination of label, sid, s_size or just distinct label with sid, s_size?

above query return you distinct of label,sid and s_size.

[DaPi]

Originally posted by DaPi
I think you are in the perfect position to find out . . . by trying it.

Or are we doing your home work for you?

[lgaorcl]

DaPi:

Thanks for the help! I tried both. The one with max(label) returned 1350 records. What does the max function do here?
Another one returned 660 records. What's the difference between these two scripts?
Do you have any good SQL books to recommend to me?

Thanks!