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" <feixion...@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
feixion...@gmail.com
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