GROUP_ID

Syntax

Description of group_id.gif follows
Description of the illustration group_id.gif

Purpose

GROUP_ID distinguishes duplicate groups resulting from a GROUP BY specification. It is useful in filtering out duplicate groupings from the query result. It returns an Oracle NUMBER to uniquely identify duplicate groups. This function is applicable only in a SELECT statement that contains a GROUP BY clause.

If n duplicates exist for a particular grouping, then GROUP_ID returns numbers in the range 0 to n-1.

Examples

The following example assigns the value 1 to the duplicate co.country_region grouping from a query on the sample tables sh.countries and sh.sales:

SELECT co.country_region, co.country_subregion,
 SUM(s.amount_sold) "Revenue",
 GROUP_ID() g
FROM sales s, customers c, countries co
WHERE s.cust_id = c.cust_id AND
 c.country_id = co.country_id AND
 s.time_id = '1-JAN-00' AND
 co.country_region IN ('Americas', 'Europe')
GROUP BY co.country_region,
 ROLLUP (co.country_region, co.country_subregion);
COUNTRY_REGION COUNTRY_SUBREGION Revenue G
-------------------- -------------------- ---------- ----------
Americas Northern America 220844 0
Americas Southern America 10872 0
Europe Eastern Europe 12751 0
Europe Western Europe 558686 0
Americas 231716 0
Europe 571437 0
Americas 231716 1
Europe 571437 1

To ensure that only rows with GROUP_ID < 1 are returned, add the following HAVING clause to the end of the statement :

HAVING GROUP_ID() < 1