Sql Distinct more than 1 coloum

Can you please elaborate on what you are after with some sample data rows?
What does that query not give you? (it has correct syntax)

i want an sql statement to display distinct rows :

here is my sql statment:


select DISTINCT  catalog_id, id from Products

outputs:  
catalog_id  id          
----------- -----------
20          25          
20          26          
20          27          
20          28          
20          29          
20          30          
20          31          
20          32          
20          33          
20          36          
20          39          
24          37          
24          38    


i want it to output  only 2 rows

catalog_id  id          
----------- -----------
20          25          
24          37

and i need to out more than 1 coloum e.g images, int varchar

can you break that code down and make it easy to under stand? please

ok thanks now i understand

you could read this article to understand:
https://www.experts-exchange.com/A_3203.html

Are these easier to understand?
Works on MySQL as well.

select * from Products
where ID in
(
select min(id)
from Products
group by catalog_id
)

or

select p.*
from
(
select min(id) as MinID
from Products
group by catalog_id
) m inner join Products p on MinID=p.id

For performance sakes, you may want to consider using an exists() based correlated sub-select to get your min IDs.  I've done some performance testing and it is going to be faster.

http://sqlservernation.com/blogs/brandongalderisi/archive/2009/09/20/using-row-number-vs-a-correlated-sub-select.aspx

thanks