将 2 个相似的更新查询合并为一个查询

Question

update support set PH1 ='0'||PH1
where PH1 is not null;


update support set PH2 ='0'||PH2
where PH2 is not null;

有没有一种方法可以将上述两个查询（更新相同的table）组合成一个查询？

Answer 1

您可以使用 case 表达式来实现这一点，例如。

UPDATE support
SET
     PH1 = CASE WHEN PH1 IS NOT NULL THEN '0'||PH1  END,
     PH2 = CASE WHEN PH2 IS NOT NULL THEN '0'||PH2  END
WHERE
     PH1 is not null OR PH2 is not null