甲骨文：解碼超過一個鍵字段

Question

我有表

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

如果 'Date_pkp' IS NULL和 'date_pkp_delete' 爲null，則 '狀態'=非PKP

如果 'Date_pkp' 是NOT NULL和 'date_pkp_delete' 不爲空，則 '狀態'=非PKP

如果 'Date_pkp' 不是null， 'date_pkp_delete' 爲空，則 '狀態'= PKP

如何使用decode查詢？從表

SELECT date_pkp，date_pkp_delete，解碼（...）狀態

Answer 1

這將是更容易被case表達要做到這一點：

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

既然你要檢查多個條件，而不是的書寫解碼，用例說明如下：

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;