“安全" TO_NUMBER() [英] "Safe" TO_NUMBER()

问题描述

SELECT TO_NUMBER('*') FROM DUAL

这显然给了我一个例外:

This obviously gives me an exception:

ORA-01722:无效的数字

ORA-01722: invalid number

有没有一种方法可以跳过"它而获得0或NULL呢?

Is there a way to "skip" it and get 0 or NULL instead?

整个问题:我有NVARCHAR2字段，其中包含数字，但几乎不包含;-)(例如*)，我需要从列中选择最大的数字.

The whole issue: I have NVARCHAR2 field, which contains numbers and not almost ;-) (like *) and I need to select the biggest number from the column.

是的，我知道这是一个糟糕的设计，但这就是我现在需要的...:-S

Yes, I know it is a terrible design, but this is what I need now... :-S

UPD :

我自己已经通过以下方式解决了这个问题

For myself I've solved this issue with

COALESCE(TO_NUMBER(REGEXP_SUBSTR(field, '^\d+')), 0)

推荐答案

我找不到比这更好的东西:

I couldn't find anything better than this:

function safe_to_number(p varchar2) return number is
    v number;
  begin
    v := to_number(p);
    return v;
  exception when others then return 0;
end;

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