sql - Oracle SQL : Group by not working with aggregates in CASE statement

Question

我的 SQL 查询当前是:

SELECT ARINVT.CLASS,
 ARINVT.ITEMNO,
 ARINVT.DESCRIP,
 ARINVT.ONHAND,
 CASE 
 WHEN DAY_USE_TOTAL.CUM_MAT_QTY IS NULL THEN 0
 ELSE SUM (DAY_USE_TOTAL.TOT_MAT_QTY) END "Material Usage"

FROM IQMS.ARINVT ARINVT
 LEFT JOIN IQMS.DAY_USE_TOTAL DAY_USE_TOTAL
    ON ARINVT.ID = DAY_USE_TOTAL.ARINVT_ID


WHERE CLASS = 'PL'
GROUP BY ARINVT.ID,
     ARINVT.CLASS,
     ARINVT.ITEMNO,
     ARINVT.DESCRIP,
     ARINVT.ONHAND

ORDER BY ARINVT.ITEMNO

我当前收到错误ORA-00979:不是 GROUP BY 表达式。 当我删除 case 语句并仅使用 SUM() 时:

SELECT ARINVT.CLASS,
 ARINVT.ITEMNO,
 ARINVT.DESCRIP,
 ARINVT.ONHAND,
 SUM (DAY_USE_TOTAL.TOT_MAT_QTY) 

FROM IQMS.ARINVT ARINVT
 LEFT JOIN IQMS.DAY_USE_TOTAL DAY_USE_TOTAL
    ON ARINVT.ID = DAY_USE_TOTAL.ARINVT_ID


WHERE CLASS = 'PL'
GROUP BY ARINVT.ID,
     ARINVT.CLASS,
     ARINVT.ITEMNO,
     ARINVT.DESCRIP,
     ARINVT.ONHAND

ORDER BY ARINVT.ITEMNO

它工作得很好。为什么是这样？我认为这是因为 CASE 语句可以返回 0，这不适用于 GROUP BY，但即使两者都作为聚合返回似乎也无法解决此问题。我该如何解决这个问题？我目前正在尝试使用子查询，但目前还没有取得多大成功。

Answer 1

这样做:

 SUM (CASE WHEN DAY_USE_TOTAL.CUM_MAT_QTY IS NULL THEN 0
 ELSE DAY_USE_TOTAL.TOT_MAT_QTY END) "Material Usage"