Jeremy Massel's Blog » Tips

Select DataSet and number of total rows with one stored procedure

jeremy.massel — Wed, 11 Aug 2010 17:16:18 +0000

when you want to write a search using .net and MSSQL, it’s a pain. This is because you’re forced to select every row in the table and then only display a small subset of it. This works okay for tables that have a few hundred rows, as query caching can make this faster. But what happens when you’re searching a table with half a million rows?

Unless you’re a complete masochist, you’re doing to want to split this into a more manageable data set, otherwise you’re gonna eat all the memory on your server. But this means that you can no longer use the DataSet.Tables[0].Rows.Count property to figure out how many rows you have. You can write a second stored procedure that’ll count the rows. But who wants to clog up their database with tons of stored procedures for no reason? Let’s consolidate it into one.

So what does this look like?

First: the stored procedure.

We’ll use output parameters to pass the row count back to our code

create procedure [dbo].[Search] @searchText varchar(512), @recordsToReturn INT, @pageNumber INT, @numberofrows INT OUTPUT AS


-- get the page we want to view

select * from

(

     select *,  ROW_NUMBER() OVER (ORDER BY creation_timestamp DESC) AS row from [table] where [table].columnName like '%' + @searchText + '%'

)

AS results WHERE row between (@pageNumber - 1) * @recordsToReturn + 1 and @pageNumber*@recordsToReturn;
-- get the total number of rows, not just the subset we want

set @numberofrows = (select count(*)  from [table] where [table].columnName like '%' + @searchText + '%')
END

Now the C# (this’ll work in VB too, but feel free to convert it yourself)

SqlConnection conn = new SqlConnection(); conn.ConnectionString = ".....your connection string here....."; conn.Open();


      DataSet returnData = new DataSet();
      SqlDataAdapter da = new SqlDataAdapter( "SearchMessages", conn);

      da.SelectCommand.CommandType = CommandType.StoredProcedure;
      da.SelectCommand.Parameters.Add("@searchText", SqlDbType.VarChar).Value = "bob";

      da.SelectCommand.Parameters.Add("@recordsToReturn", SqlDbType.Int).Value = 10;

      da.SelectCommand.Parameters.Add("@pageNumber", SqlDbType.Int).Value = 1;
      //number of rows

      SqlParameter outputParameter = new SqlParameter("@numberofrows", SqlDbType.Int, 2);

      outputParameter.Direction = ParameterDirection.Output;  
      da.SelectCommand.Parameters.Add(outputParameter);
      da.Fill(returnData, "theData");
      int numberOfRowsInDataSet = (int)outputParameter.Value;

da.Dispose(); conn.Close();

Best of luck! As always, leave a message in the comments if you have questions

MySQL Duplicate Function

jeremy.massel — Fri, 09 Jul 2010 17:13:13 +0000

Sometimes you want the ability to duplicate (clone) entities in mySQL. But duplicating their children can be a huge pain! Here’s how:


/* parent table */

insert into [parent table]

select 0, [field1, field2, field3] from [tablename] where [parent table primary key] = [parent table object ID]
/* child table */

insert into [child table]

select 0, [field1, field2, field3], (select max([parent table primary key]) from [parent table]) from [child table] where [parent table primary key] = [parent table object ID]

important note! make sure that you don’t select the primary key of the table. instead, select 0, and the auto_increment function will automatically figure out the correct primary key

As always, if you have questions, post em in the comments!

WordPress Multi Page Posts

jeremy.massel — Wed, 23 Jun 2010 16:57:51 +0000

So, multi paged posts in WordPress. That would be a handy feature, right?

Well it turns out it’s been around since at least 2007. Just found out about it today though. “How do I use it?” you ask?

Simply put

into your post. This tag acts as a page break. Done!

Batch Delete Performance SQL Server

jeremy.massel — Thu, 17 Jun 2010 17:38:32 +0000

Deleting old records from a table with > 3 000 00 rows. What’s the best way to do this?

It seems the fastest way to do this is simply to:
delete from [table] where creation_timestamp < dateadd (mm, -6, getdate())
(deleting anything older than 6 months)

It took 3 hours (10916 seconds to be exact) to delete 1.6 million (1,619,433) records this way. (148.35 / second).

We needed to do a second batch the next day, but wanted to split it into batches to try to get better performance.

Running:

delete from [table] where pk_id in( select pk_id from ( SELECT ROW_NUMBER() OVER (ORDER BY creation_timestamp desc) AS RowNumber, pk_id FROM [table] where creation_timestamp < '2009-12-16 13:52:08.673') _objectsToDelete WHERE RowNumber between 1 and 100000)

takes 12 minutes. (732 seconds) (136.61 / second).

Strangely, using the TOP command with a subquery takes the longest:

delete from [table] where pk_id in (select TOP 100000 pk_id from [table] where creation_timestamp < '2009-12-16 13:52:08.673')

15 minutes (904 seconds) (110.61 / second)

Have a better way? Let me know in the comments!

Xcode Fix Recent Projects Empty

jeremy.massel — Thu, 15 Apr 2010 23:30:57 +0000

Terminal Command:
defaults write com.apple.Xcode NSRecentDocumentsLimit -int 10

Relaunch Xcode. Done.

New Favourite Terminal Command

jeremy.massel — Wed, 24 Mar 2010 23:43:30 +0000

Best command ever:

sudo !!

Tells the terminal to run the last command again, but to throw sudo in front of it.

obligatory XKCD link:

http://xkcd.com/149/

Run JavaScript function every n seconds

jeremy.massel — Mon, 11 Jan 2010 19:15:55 +0000

//tell javascript to run a function in 1 second setTimeout ("myFunction()", 1000 );


function myFunction(){

        //do stuff
        //once the function is finished, queue this function up to run again in 1 second

	setTimeout ( "myFunction()", 1000 );

}

Get latitude and longitude of an address using google maps

jeremy.massel — Sun, 13 Sep 2009 04:33:51 +0000

Google doesn’t make it easy to show you the latitude and longitude of an address you search in google maps, but there’s an easy way to get the info.

go to google maps, type the address, and click search
once you’ve found it, go to your address bar and clear what’s in it
paste: javascript:void(prompt('',gApplication.getMap().getCenter())); into the address bar
use the coordinates for whatever you wish!

VirtualHostX and mod_rewrite

jeremy.massel — Thu, 13 Aug 2009 20:41:58 +0000

To enable mod_rewrite manually, see: OS X server tips but if you are using VirtualHostX it changes your default config file. Add the following code to the Directives box:
Options FollowSymLinks AllowOverride All AuthConfig Order deny,allow Deny from all

if you’re using the new version of VirtualHostX, make sure that you select Directory from the dropdown, then use:
Options FollowSymLinks AllowOverride All AuthConfig

Embedding Web Fonts: A cautionary tale

jeremy.massel — Wed, 08 Jul 2009 21:14:46 +0000

So for work, the designer says “Hey, can we use this font in the webpage” and like an idiot, I say “sure, why not?”. Well, FF and Safari don’t support .otf files (for whatever reason) So I download FontForge, open it in X11 (on my mac) and convert it to .ttf, which works great.

Then I messed around in IE, trying to make it work, even downloading this tool:

Worst thing EVER. Don’t do this. Don’t get this. Don’t even look at this. You will feel violated if you use it.

So…how to embed an OTF font in a website (make sure you have a license to do so kids):

Convert OTF file to .ttf (use fontForge)
Embed with @font-face
When adding the font to a style, in IE you CAN NOT call it by the name you gave it with the @font-face declaration. You have to call it by it’s name. So if the font’s name is myfontLTSTDBOLDITALICROMAN you have to do: body{ font-family: myfontLTSTDBOLDITALICROMAN; } Sucky? Very. Works? yes.

Have a nice day