sum, min, max and null
От | Nagy László Zsolt |
---|---|
Тема | sum, min, max and null |
Дата | |
Msg-id | 53F24431.9030801@shopzeus.com обсуждение исходный текст |
Ответы |
Re: sum, min, max and null
Re: sum, min, max and null |
Список | pgsql-admin |
Hi, I understand that sum, min and max ignore null values. So for example this query: select sum(v),min(v) from ( select 1 as v union all select null union all select 3 ) s will result in sum(v)=4 , min(v)=1. However, I'm in need of a different interpretation, where sum() should change the output value to null if there is any NULL value in the input. How do I achieve this? I was experimenting with this: select case when sum(hasnull)>0 then null else sum(v) end as mysum from ( select v, case when v is null then 1 else 0 end as hasnull from ( select 1 as v union all select null union all select 3 ) s ) s2 It works but this is so ugly that I'm not even trying to use it in production code. Is there any better way to do it? Thanks, Laszlo
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