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From: Stanton Schmidt <sschmidt@rgllogistics.com>
To: Martin Stöcker <martin.stoecker@stb-datenservice.de>
Cc: pgsql-sql <pgsql-sql@lists.postgresql.org>
Subject: Re: Query question
Date: Thu, 8 Mar 2018 13:17:07 -0600 (CST)
Message-ID: <557870630.48523473.1520536627693.JavaMail.zimbra@rglholdings.com> (raw)
In-Reply-To: <e22d829f-77f2-86c9-e89d-6885bc1fc56d@stb-datenservice.de>
References: <415803152.48510563.1520535505737.JavaMail.zimbra@rglholdings.com>
	<e22d829f-77f2-86c9-e89d-6885bc1fc56d@stb-datenservice.de>

So far I have been unable to figure out how to do that. 

I tried: 
select a.equipment_id, b.log_date, b.log_time, b.event_desc 
from (select distinct equipment_id from log_table) a 
, (select equipment_id, log_date, log_time, event_desc from log_table order by log_date desc, log_time desc limit 5) b 
where a.equipment_id = b.equipment_id 

but all I end up with is 5 total records. 

Stanton 

From: "Martin Stöcker" <martin.stoecker@stb-datenservice.de> 
To: "pgsql-sql" <pgsql-sql@lists.postgresql.org> 
Sent: Thursday, March 8, 2018 1:07:30 PM 
Subject: Re: Query question 

My first idea is to select all equipments and lateral join them to the 5 most recent events 

Regards Martin 

Am 08.03.2018 um 19:58 schrieb Stanton Schmidt: 



Hi, 
I am new to the list so feel free to let me know if I am out of line. 

My question is: 
I have a table that has log events for pieces of equipment. For each piece of equipment this table may contain 1 or more (hundreds potentially). 
I need to write a query that will return only the last 5 log events for each (and every) piece of equipment. 

log_table ( 
equipment_id character(30), 
log_date date, 
log_time time, 
event_desc text 
) 

Thanks for your help. 

stanton schmidt 
Database Administrator 
direct. [ callto:920.884.1281 | 920. ] 471.4495 cell 920.660.1828 

RGL 
GO AHEAD. ASK WHAT IF. 
[ http://www.rgllogistics.com/ | www.RGLlogistics.co
                          m ] 

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