How Can I Concatenate and Group Query Results in Oracle?

Concatenating and Grouping Query Results in Oracle

When dealing with data in Oracle tables, concatenate and grouping rows can be invaluable for organizing and analyzing information. Suppose you have a table with columns for names and corresponding group names.

To retrieve the names concatenated within the respective group names, you can utilize the LISTAGG function if you're using Oracle 11g or higher:

SELECT
group_name,
LISTAGG(name, ', ')
WITHIN GROUP (ORDER BY GROUP) "names"
FROM name_table
GROUP BY group_name

This query will group the names by their corresponding group names and return the concatenated names. However, if you're not using Oracle 11g, consider using analytics instead:

select grp,
    ltrim(max(sys_connect_by_path
       (name, ',' )), ',')
        scbp
  from (select name, grp,
            row_number() over
           (partition by grp
            order by name) rn
         from tab
          )
start with rn = 1
connect by prior rn = rn-1
and prior grp = grp
  group by grp
  order by grp

This query will also concatenate the names within their respective group names, using analytics to handle the grouping.

By utilizing these techniques, you can efficiently concatenate and group data in Oracle, making it easier to analyze and present information in a meaningful way.

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