Question

如果DB2查询中没有结果，我试图显示“0”。 Coalesce不适合我。这是DB2 LUW v8.2。我怎么能这样做？

SELECT 'Stuff',
COALESCE((SUM(OI.QUANTITY)),0)
FROM DB2ADMIN.ORDERS O INNER JOIN DB2ADMIN.ORDERITEMS OI ON O.ORDERS_ID = OI.ORDERS_ID
WHERE DATE(O.TIMEPLACED) = (DATE(CURRENT DATE) - 1 DAYS)
AND OI.CATENTRY_ID = 000001    
GROUP BY DATE(O.TIMEPLACED)

Answer 1

您可以使用Common Table Expression执行此操作。

WITH MYCTE (MYSTUFF, MYSUM) AS (
SELECT 'Stuff',0
FROM SYSIBM.SYSDUMMY1
UNION ALL
SELECT 'Stuff', SUM(OI.QUANTITY)
FROM DB2ADMIN.ORDERS O INNER JOIN DB2ADMIN.ORDERITEMS OI ON O.ORDERS_ID = OI.ORDERS_ID
WHERE DATE(O.TIMEPLACED) = (DATE(CURRENT DATE) - 1 DAYS)
AND OI.CATENTRY_ID = 000001    
GROUP BY DATE(O.TIMEPLACED))
SELECT MYSTUFF, SUM(MYSUM)          
FROM MYCTE
GROUP BY MYSTUFF;

Answer 2

可能Coalesce正在工作，但总和因为null而失败，你是否尝试在SUM中使用COALESCE或NVL？即

SELECT 'Stuff',
(SUM(COALESCE(OI.QUANTITY,0)))
FROM DB2ADMIN.ORDERS O INNER JOIN DB2ADMIN.ORDERITEMS OI ON O.ORDERS_ID = OI.ORDERS_ID
WHERE DATE(O.TIMEPLACED) = (DATE(CURRENT DATE) - 1 DAYS)
AND OI.CATENTRY_ID = 000001    
GROUP BY DATE(O.TIMEPLACED)

无法使用DB2 Coalesce

2 个答案: