From: Pavel Stehule <pavel.stehule@gmail.com>
To: Feixiong Li <feixiongli@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: How to max() make null as biggest value?
Date: Tue, 20 Apr 2010 17:17:53 +0200
Message-ID: <s2z162867791004200817j80b0a976u9979bfc7e7d73f25@mail.gmail.com> (raw)
In-Reply-To: <2A8BBCA2-814C-4E8D-BCE1-11FA2F8D120E@gmail.com>
References: <2A8BBCA2-814C-4E8D-BCE1-11FA2F8D120E@gmail.com>
Hello
2010/4/14 Feixiong Li <feixiongli@gmail.com>:
> 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?
>
max() returns max value of some column
create table foo(a int);
insert into foo values(10);
insert into foo values(33);
postgres=# select * from foo;
a
----
10
33
(2 rows)
Time: 0,524 ms
postgres=# select max(a) from foo;
max
-----
33
(1 row)
there is function greatest
postgres=# select greatest(1,2,34,2,1);
greatest
----------
34
(1 row)
regards
Pavel Stehule
> 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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Subject: Re: How to max() make null as biggest value?
In-Reply-To: <s2z162867791004200817j80b0a976u9979bfc7e7d73f25@mail.gmail.com>
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