Oracle® Database SQL Reference 10g Release 2 (10.2) Part Number B14200-02 |
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Syntax
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