Help with query to return results from group within table?

Question

Hi
Im a total noob, so please be gentle....!
I am looking at a table that has a WORD column and a WORD_TYPE_ID column.
Words can have the same type_id.
What I am trying to do is write a query that will return the longest word for each word_type_id.
I have been trying for hours to get this and all I seem to get is either error messages or I return the longest word in the whole WORD column.
The furthest I can get before things break down is.....
select word
from table
where
length(word) =
select
max(length(word))
from table
Any help on this or if I could be pointed in the right direction it would be greatly appreciated.
Thanks

Answer 1

Hi,
Welcome to the forum!
Here's one way:
SELECT    word_type_id
,       MIN (word) KEEP (DENSE_RANK LAST ORDDER BY LENGTH (word))     AS longest_word
FROM       table_x
GROUP BY  word_type_id;If there happens to be a tie within some word_type_id (that is, 2 or more words have exactly the same length, which is the longest in that group) the expression above will return the first one, in alphabetic order. (That's what MIN means here.)
Edited by: Frank Kulash on Aug 11, 2009 1:56 PM
You almost had it.
As you noticed, you were getting the longest row in the whole table. That's because your sub-query was looking at the whole table.
If you correlate the sub-query to the row in the main table, as shown below, you can get the longest word in each group:
select  word
from     table     m                              -- m for main
where      length (word) = (
                            select  max (length(word))
               from     table
               where     word_type_id  = m.word_type_id     -- New
               );