Comments on: SELECT TOP 1 http://sqlserverplanet.com/tsql/select-top-1 Tips and Articles on SQL Server Wed, 16 May 2012 18:08:18 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: TradeItEasy http://sqlserverplanet.com/tsql/select-top-1/comment-page-1#comment-1178 TradeItEasy Tue, 24 Apr 2012 12:30:46 +0000 http://sqlserverplanet.com/?p=1364#comment-1178 Just to add a Stat here: On my Computer the Nested Select has a Cost of 0.00677 whereas the Top 1 Select has a cost of 0.01485 because sorting the table alone costs you 0.01154. Sorting is very Time and Processor Intensive as you need to compare two values over and over again which means you go through your result set several times. So be aware of what you sort! A tip for those who would like to compare two methods of Querying: Type your two Statements in the Query and look at the execution plan. It will tell you which query took how much of the whole Batch. In my example the Nested Select took 31% of the Batch and the Top 1 took 69%... Just to add a Stat here:

On my Computer the
Nested Select has a Cost of 0.00677
whereas the
Top 1 Select has a cost of 0.01485
because sorting the table alone costs you 0.01154. Sorting is very Time and Processor Intensive as you need to compare two values over and over again which means you go through your result set several times. So be aware of what you sort!

A tip for those who would like to compare two methods of Querying: Type your two Statements in the Query and look at the execution plan. It will tell you which query took how much of the whole Batch. In my example the Nested Select took 31% of the Batch and the Top 1 took 69%…

]]> By: TradeItEasy http://sqlserverplanet.com/tsql/select-top-1/comment-page-1#comment-1177 TradeItEasy Tue, 24 Apr 2012 12:17:34 +0000 http://sqlserverplanet.com/?p=1364#comment-1177 I would generally prefer to do the nested Select option as it takes only half the time. Using the Top 1 Method may be convenient for Coding but does not pay off when it comes to runtime efficiency... Always ask the query analyzer first ;-) I would generally prefer to do the nested Select option as it takes only half the time.

Using the Top 1 Method may be convenient for Coding but does not pay off when it comes to runtime efficiency…

Always ask the query analyzer first ;-)

]]> By: Max http://sqlserverplanet.com/tsql/select-top-1/comment-page-1#comment-1173 Max Thu, 19 Apr 2012 18:37:50 +0000 http://sqlserverplanet.com/?p=1364#comment-1173 Brenda, select max(date),event from eventTable group by event or select top 1 date, event from eventTable group by event order by date desc Brenda,
select max(date),event
from eventTable
group by event

or

select top 1 date, event
from eventTable
group by event
order by date desc

]]> By: Brenda http://sqlserverplanet.com/tsql/select-top-1/comment-page-1#comment-868 Brenda Tue, 20 Sep 2011 11:53:54 +0000 http://sqlserverplanet.com/?p=1364#comment-868 How can I find the most recent date of a repeating event? How can I find the most recent date of a repeating event?

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