关系运算符问题为空

Question

我在插入关系运算符时遇到以下选择语句无法拾取数据的问题。

SELECT C.FIRST_NAME, C.LAST_NAME, B.COMPANY,A.ITEMNO, A.REV, A.DESCRIP
FROM  ARINVT A
INNER JOIN ARCUSTO B 
  ON A.ARCUSTO_ID = B.ID
INNER JOIN PR_EMP C 
  ON B.AR_PR_EMP_ID = C.ID
WHERE A.ARCUSTO_ID = B.ID AND
  B.AR_PR_EMP_ID = C.ID AND
  A.ONHAND <= 0 AND
  A.CUSER7 = 'Y' AND
  A.PK_HIDE <> 'Y'

如果删除语句的最后一行（A.PK_HIDE <>'Y'），它将获取我希望看到的数据。 PK_HIDE列中只有3个不同的值，即“ Y”，“ N”或Null。 当删除最后一行时，我选择PK_HIDE ='N'的数据集。

我也尝试过以下语句：

SELECT C.FIRST_NAME, C.LAST_NAME, B.COMPANY,A.ITEMNO, A.REV, A.DESCRIP
FROM  ARINVT A
INNER JOIN ARCUSTO B 
  ON A.ARCUSTO_ID = B.ID
INNER JOIN PR_EMP C 
  ON B.AR_PR_EMP_ID = C.ID
WHERE A.ARCUSTO_ID = B.ID AND
  B.AR_PR_EMP_ID = C.ID AND
  A.ONHAND <= 0 AND
  A.CUSER7 = 'Y' AND
  A.PK_HIDE = 'N' OR A.PK_HIDE IS NULL

该语句似乎忽略了(A.CUSER7 = 'Y')因为它拉取了所有A.PK_HIDE = 'N'或A.PK_HIDE IS NULL数据集。

任何帮助表示赞赏。 先感谢您。

Answer 1

如果要在第一个查询中正确管理空值，则应将NVL用于PK_HIDE

SELECT C.FIRST_NAME, C.LAST_NAME, B.COMPANY,A.ITEMNO, A.REV, A.DESCRIP
FROM  ARINVT A
INNER JOIN ARCUSTO B 
  ON A.ARCUSTO_ID = B.ID
INNER JOIN PR_EMP C 
  ON B.AR_PR_EMP_ID = C.ID
WHERE A.ARCUSTO_ID = B.ID 
AND B.AR_PR_EMP_ID = C.ID 
AND A.ONHAND <= 0 
AND A.CUSER7 = 'Y' 
AND NVL(A.PK_HIDE, 'N') <> 'Y'

在第二个步骤中，您必须在（）中包装PK_HIDE的条件

SELECT C.FIRST_NAME, C.LAST_NAME, B.COMPANY,A.ITEMNO, A.REV, A.DESCRIP
FROM  ARINVT A
INNER JOIN ARCUSTO B 
  ON A.ARCUSTO_ID = B.ID
INNER JOIN PR_EMP C 
  ON B.AR_PR_EMP_ID = C.ID
WHERE A.ARCUSTO_ID = B.ID 
AND B.AR_PR_EMP_ID = C.ID 
AND A.ONHAND <= 0 
AND A.CUSER7 = 'Y' 
AND ( A.PK_HIDE = 'N' OR A.PK_HIDE IS NULL) 

如果您不使用( A.PK_HIDE = 'N' OR A.PK_HIDE IS NULL) ，则where条件等于

WHERE ( A.ARCUSTO_ID = B.ID 
AND B.AR_PR_EMP_ID = C.ID 
AND A.ONHAND <= 0 
AND A.CUSER7 = 'Y' 
AND A.PK_HIDE =  ) 
OR A.PK_HIDE IS NULL

显然会产生错误的结果