Oracle sql group by then sort

Question

I'm trying to split my query results into 2 groups, ones that have a flag of Y and ones that have a flag N. I then need to sort the groups by the based on 2 things.

Here's the query I've tried which doesn't work with the GROUP BY bit:

SELECT      location, 
        country 
FROM        web_loc_info 
WHERE       flag = 'Y' 
OR      flag = 'N' 
AND         available_online = 'Y' 
GROUP BY    flag 
ORDER BY    country, 
                location_desc

Any help with this would be great so thanks in advance for any replies

Answer 1

It might be worth clarifying that a "GROUP" in Oracle (from a GROUP BY operation) is where one or more rows of raw data has been consolidated into a single row in the result.

Recall that:

SELECT flag FROM web_loc_info GROUP BY flag ORDER BY flag

is equivalent to

SELECT DISTINCT flag FROM web_log_info ORDER BY flag

(If the flag column only contains Y and N values, both queries will return 2 rows.)

So, in the future, when you think "group" ask if you mean "summarize the data so that there's one row for each group value" (in this case the "Y"/"N" values in the flag column) in which case the GROUP BY clause is probably what you're after or if you just want to put sort rows with the same values together in which case you're just looking at ORDER BY .

I'd say Randy and Harshit above are pretty close only I'd include the FLAG column in the SELECT list so you can see what "group" the LOCATION and COUNTRY values belong to (and making it obvious where the break in the grouping occurs):

SELECT      flag,
            location, 
            country 
FROM        web_loc_info 
WHERE       flag IN ('Y', 'N')
AND         available_online = 'Y' 
ORDER BY    flag, -- DESC if you want the Y rows to show first
            location, -- DESC? or is there actually a column called LOCATION_DESC?
            country

Answer 2

it doesn't seem like you need the group at all.

SELECT      location, 
            country 
FROM        web_loc_info 
WHERE       flag in ( 'Y' , 'N' )
AND         available_online = 'Y' 
ORDER BY    flag desc,
            country, 
            location_desc

Answer 3

Can try this

SELECT location, country FROM web_loc_info WHERE flag = 'Y' OR flag = 'N' AND     
available_online = 'Y'  ORDER BY FLAG,country, location_desc

Answer 4

All columns you select need to be in your group by, unless you aggregate over them. So in this case, your query would become:

SELECT      location, 
            country 
FROM        web_loc_info 
WHERE       flag = 'Y' 
OR          flag = 'N' 
AND         available_online = 'Y' 
GROUP BY    flag,
            location, 
            country,
            location_desc
ORDER BY    country, 
            location_desc

location_desc is needed as well, because you use it in order by .