I have a table:
abc_test with columns n_num, k_str.
This query doesnt work:
select distinct(n_num) from abc_test order by(k_str)
select n_num from abc_test order by(k_str)
As far as i understood from your question .
distinct :- means select a distinct(all selected values should be unique). order By :- simply means to order the selected rows as per your requirement .
The problem in your first query is For example : I have a table
ID name 01 a 02 b 03 c 04 d 04 a
now the query
select distinct(ID) from table order by (name) is confused which record it should take for ID - 04 (since two values are there,d and a in Name column). So the problem for the DB engine is here when you say
order by (name).........