Re: How to max() make null as biggest value?

Howdy, Feixiong.

I dunno if this results out of the box, but try something like this

SELECT CASE WHEN (COUNT(*) <> COUNT("YourColumnName")) THEN NULL ELSE 
MAX("YourColumnName") END AS "...."
FROM t_your_table;

I don't have an example table to test so this is "air code", but if you use 
count on a column with nulls the return value is different from count(*)

HTH

Best,
Oliveiros Cristina

----- Original Message ----- 
From: "Feixiong Li" <feixiongli@gmail.com>
To: <pgsql-sql@postgresql.org>
Sent: Wednesday, April 14, 2010 5:33 AM
Subject: [SQL] How to max() make null as biggest value?


> Hi , guys ,
>
> I am newbie for sql, I have a problem when using max() function, I  need 
> get null when there are null in the value list, or return the  largest 
> value as usual, who can do this?
>
> i.e.  max([1,2,3,4,5]) => 5
> max([1,2,3,4,5,null]) => null
>
> thanks in advance!
>
> Feixiong
> feixiongli@gmail.com
>
>
>
>
>
>
>
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