Journey of a Software Developer » TSQL http://www.tyronedavisjr.com HTML | CSS | JavaScript | ASP.NET | PHP | C# | Java | VB.NET | MS SQL | MySQL | Flash Sun, 17 Apr 2011 03:51:52 +0000 en hourly 1 http://wordpress.org/?v=3.0.1 TSQL, Looping through a result set without using database cursor http://www.tyronedavisjr.com/2007/12/12/tsql-looping-through-a-result-set-without-using-database-cursor/ http://www.tyronedavisjr.com/2007/12/12/tsql-looping-through-a-result-set-without-using-database-cursor/#comments Wed, 12 Dec 2007 18:18:56 +0000 admin http://www.tyronedavisjr.com/index.php/2007/12/12/tsql-looping-through-a-result-set-without-using-database-cursor/ A few years ago a project that I was working on required me to loop through a result set from a select statement.  Most examples that I saw used database cursors. However, I came across an old article that shows an alternative method for doing this.  Let’s say we have a table that looks like this:

Table Name : Contacts

ID FirstName LastName EmailAddress
1 Jack Bauer jbauer@fox24.com
2 Dan Marino dmarino@dolphins.com
3 George Bush gbush@whitehouse.gov
4 Michael Jordan mjordan@bulls.com
5 Bill Clinton bj@whitehouse.gov

 

Please don’t pay attention to the names. I’m sure you did so already. Anyway, let’s pretend that we had a scenario that we want to loop over the rows in this table and send an email out to these individuals.  We can do this without using a database cursor. Here is some code to ponder on:

 
   1:  declare @email varchar(20)
   2:  declare @id int
   3:  declare @rowNum int
   4:  declare @maxrows int
   5:   
   6:  select top 1 @id = ID, @email = EmailAddress from Contacts
   7:  select @maxRows = count(*) from Contacts
   8:   
   9:  set @rowNum = 0
  10:   
  11:  -- this will until the last row is reached
  12:  WHILE @rowNum < @maxRows
  13:   BEGIN
  14:      set @rowNum = @rowNum + 1
  15:      -- this is where you can now do something like sending an email
  16:      -- for now, we will just print the email to the output screen
  17:      print ('Sending email to: ' + @email)
  18:   
  19:      -- now we grab the next row making sure the ID of the next row
  20:      -- is greater than previous row
  21:      select top 1 @id = ID, @email = EmailAddress from Contacts where ID > @id
  22:   END
 

I have tried to include additional comments in this code snippet so that it doesn’t require much explanation. However, you can see the original article if you need additional details.. Until next time…

 

Happy Coding!

 

 

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