我從表中刪除，如果一列是 null 我需要使用另一列

Question

DELETE FROM HERAPERM.SCRUBLITST
WHERE
    CASE 
       WHEN ODUDAT IS NOT NULL
          THEN ODUDAT > to_char(current_date - 2 month, 'MM')   
       ELSE ODCDAT > to_char(current_date - 2 month, 'MM')         
    END

Answer 1

這是獲得所需結果的一種方法。 創建一個臨時表來保存要刪除的行的主鍵，然后在將它們全部收集后從表中刪除它們。

DECLARE @foundIDs TABLE ( ID INT )

INSERT INTO @foundIDs
SELECT ID FROM HERAPERM.SCRUBLITST
WHERE ODUDAT IS NULL
AND ODUDAT > to_char(current_date - 2 month, 'MM')

INSERT INTO @foundIDs
SELECT ID FROM HERAPERM.SCRUBLITST
WHERE ODUDAT IS NOT NULL
AND ODCDAT > to_char(current_date - 2 month, 'MM')

DELETE FROM HERAPERM.SCRUBLITST
WHERE ID IN (SELECT ID FROM @foundIDs)

在關於無法在 DB2 中聲明臨時表的評論之后，這里是另一種方法：

DELETE FROM HERAPERM.SCRUBLITST
WHERE ID IN (SELECT ID FROM HERAPERM.SCRUBLITST
    WHERE ODUDAT IS NULL
    AND ODUDAT > to_char(current_date - 2 month, 'MM'))
OR ID IN (SELECT ID FROM HERAPERM.SCRUBLITST
    WHERE ODUDAT IS NOT NULL
    AND ODCDAT > to_char(current_date - 2 month, 'MM'))

Answer 2

沒有相關子查詢和需要 ID 的更簡單的解決方案：

DELETE FROM HERAPERM.SCRUBLITST
WHERE COALESCE (ODUDAT, ODCDAT) > to_char(current_date - 2 month, 'MM');