Re: Help with a SQL query

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От Mark Nielsen
Тема Re: Help with a SQL query
Дата
Msg-id 3C62EB58.7050004@kepnet.net
обсуждение исходный текст
Список pgsql-sql
Dan Smith wrote:

> Can someone help me figure out a SQL query to do this?
> 
> I have a table with 3 columns: date, count, host.  It records the
> number of operations per day by a specific host.  There are usually 3
> or 4 entries per day per host.  I can do max(count)-min(count) to
> figure out how many operations per day were completed.  What I need is
> a query that will output 3 columns: date, host1, host2; the rows will
> be the per-day counts.  For example:
> 
> Date    Host1   Host2
> ----    -----   -----
> Feb-2   25      19
> Feb-3   20      29
> Feb-4   4       18


It is a pretty long sql command, but basically,
1. select a list of unique dates, then select a list of unique hosts, 
and then select a count for the hits per host per date. I don't think it  is easy to list it out the way you want since
thereare an unknown 
 
number of hosts. I would create an sql query to list it out
date host value
instead. Then, use your scripting language to organize the data the way
you want it. THe problem is you have an unknow number of hosts.
I would just use a perl script (or python, php), to select the 
information, add it up, and the reformat it to print it out in the way 
you want. I wouldn't bother doing this all in sql. I think some of it 
has to be done in a programming language.

But I am not a total guru, so maybe there is a way.
Mark





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