Question

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Date_pkp  | date_pkp_delete | status
<null>    |  <null>         |
10.10.2000| 20.11.2009      |
12.10.2005| <null>          |

如果＆＃39; Date_pkp＆＃39;为空且＆＃39; date_pkp_delete＆＃39;是空的然后状态＆＃39; =非PKP

如果＆＃39; Date_pkp＆＃39;不为空且＆＃39; date_pkp_delete＆＃39;不是空的，那么＆＃39; status＆＃39; =非PKP

如果＆＃39; Date_pkp＆＃39;不为空且＆＃39; date_pkp_delete＆＃39;为空，然后是状态＆＃39; = PKP

如何使用decode进行查询？

从表中选择date_pkp，date_pkp_delete，Decode（...）状态

Answer 1

使用case表达式执行此操作会更容易：

SELECT date_pkp,
       date_pkp_delete
       CASE WHEN ((date_pkp IS NULL AND date_pkp_delete IS NULL) OR
                  (date_pkp IS NOT NULL AND date_pkp_delete IS NOT NULL))
            THEN 'Non PKP'
            WHEN (date_pkp IS NOT NULL AND date_pkp_delete IS NULL)
            THEN 'PKP'
       END AS status
FROM   my_table

Answer 2

由于您必须检查多个条件，而不是编写complected decode，请使用case语句，如下所示：

select DATE_PKP, DATE_PKP_DELETE, case when (DATE_PKP is null and DATE_PKP_DELETE is null) then  'Non PKP'
                                       when (DATE_PKP is not null and DATE_PKP_DELETE is not null) then 'Non PKP'
                                       when (DATE_PKP is not null and DATE_PKP_DELETE is null) then 'PKP status' 
                                   end STATUS
from table;

Oracle：解码多个关键字段

2 个答案: