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C# Nested While loops and datareader problem

HI I am working with datareader. I have 2 seperate connections strings and cmds executing /
setup so I can do the different reads.

I get multiple results for the first datareader (dr) and I know the single record in the
dr3 datareader will match one of the values but the second while loop doesn't re-read the
same single piece of data. Shouldn't the while loop cause the datareader (dr3) to re-read
and recompare the result?

Thanks

Baz
While (dr.Read())
 
{
	while (dr3.Read())
	{
	
      if (dr3["data"].ToString() == dr["otherdata"].ToString())
 
	{
 
	//do something
 
	}
 
	}
}

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0
ipgbarry
Asked:
ipgbarry
3 Solutions
 
MatthiasVanceCommented:
You will need to 'reset' the dr3 datareader, because it will loop until the end of the records, and then it has no data left, so it will not loop the next time the dr.read() loop iterates.

Kind regards,

Matthias Vance
0
 
Arthur_WoodCommented:
A Datareader is read-only, foreward-only.  There is no way to reset the datareader back to the beginning, and re-read it.  I would copy the values from the second datareader into an array.
 
AW
 
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Anurag ThakurTechnical ManagerCommented:
i agree with the comments of MatthiasVance & Arthur_Wood - as the SqlDataReader is a forward only and once it reaches to the end as in your inner while loop you cannot reset it back to the beginning.

i recommend that as you are doing operations in a connected mode (data readers have a open connection to the database), try doing your operations in a disconnected mode by using data table or a dataset. The operations using a dataset/datatable can be a little slower but they provide you with the flexibility of kind of operations you want to do - as is your requirement
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ipgbarryAuthor Commented:
Thanks eveyone this has really helped!
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