この例では、拡張が発生した後、VantageがDISTINCT操作を行なう方法を示します。
CREATE SET TABLE products ( product_id INTEGER, product_price DECIMAL(5,2), product_duration PERIOD(DATE)) PRIMARY INDEX (product_id);
製品に次の行があると仮定します。
product_id ---------- |
product_price ------------- |
product_duration ---------------- |
1000 | 100.00 | 2007-02-15, 2007-08-11 |
1001 | 99.99 | 2007-03-04, 2007-05-01 |
1001 | 101.10 | 2008-05-10, 2009-05-10 |
1001 | 1-4.10 | 2007-07-16, 2008-10-09 |
クエリー式内にDISTINCT演算子を指定し、クエリーの選択リスト内の拡張された列を指定すると、データベースは、この例で示すように、拡張後にそのDISTINCT操作を実行し、拡張された結果から重複する行を削除します。
SELECT DISTINCT product_id, pd FROM products EXPAND ON product_duration AS pd BY ANCHOR PERIOD MONTH_BEGIN;
SELECT文は、次の応答セットを返します。
product_id | pd |
1000 | 2007-02-01, 2007-03-01 |
1000 | 2007-03-01, 2007-04-01 |
1000 | 2007-04-01, 2007-05-01 |
1000 | 2007-05-01, 2007-06-01 |
1000 | 2007-06-01, 2007-07-01 |
1000 | 2007-07-01, 2007-08-01 |
1000 | 2007-08-01, 2007-09-01 |
1001 | 2007-03-01, 2007-04-01 |
1001 | 2007-04-01, 2007-05-01 |
1001 | 2008-05-01, 2008-06-01 |
1001 | 2008-06-01, 2008-07-01 |
1001 | 2008-07-01, 2008-08-01 |
1001 | 2008-08-01, 2008-09-01 |
1001 | 2008-09-01, 2008-10-01 |
1001 | 2008-10-01, 2008-11-01 |
1001 | 2008-11-01, 2008-12-01 |
1001 | 2008-12-01, 2009-01-01 |
1001 | 2009-01-01, 2008-02-01 |
1001 | 2009-02-01, 2009-03-01 |
1001 | 2009-03-01, 2009-04-01 |
1001 | 2009-04-01, 2009-05-01 |
1001 | 2009-05-01, 2009-06-01 |
1001 | 2007-07-01, 2007-08-01 |
1001 | 2007-08-01, 2007-09-01 |
1001 | 2007-09-01, 2007-10-01 |
1001 | 2007-10-01, 2007-11-01 |
1001 | 2007-11-01, 2007-12-01 |
1001 | 2007-12-01, 2008-01-01 |
1001 | 2008-01-01, 2008-02-01 |
1001 | 2008-02-01, 2008-03-01 |
1001 | 2008-03-01, 2008-04-01 |
1001 | 2008-04-01, 2008-05-01 |