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I have a datareader. I need to find the number of rows in it so that I can instantiate an array. Initially I did this by using:

<code>
DataTable dt = new DataTable();
dt.Load(reader);
int noOfRows = dt.Rows.Count; 
</code>

However I found that loading the reader into the datatable will close the reader before I am able to iterate through it later in my code. I was thinking of cloning the reader and passing the clone to the Datatable. Is this possible or advisable?

Is there a better way of finding the number of rows in my data reader? I know I could do something with a list (not fully sure what) but my datareader contains 33 fields of varying data types and I dont know how to put that all into a list.

thanks

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  • No it is just a one off query. The project is really small. The query is a basic SELECT tablexxx FROM WHERE. Can i use the SET NOCOUNT ON on this? SQL isnt really my thing. Commented Jun 9, 2016 at 13:17
  • You could just use your DataTable now that it is full. Commented Jun 9, 2016 at 13:17
  • 2
    Once you have loaded the DataTable with the reader you don't need anymore the reader. Just use the DataTable Rows, all data is there. Commented Jun 9, 2016 at 13:18
  • If I am using the following to run through my datareader how would I change this to be the datatable. <code> while (reader.Read() && (i != noOfRows)) </code> In other words how do i loop a datatable? Commented Jun 9, 2016 at 13:22
  • Ill do it as foreach loop Commented Jun 9, 2016 at 13:26

1 Answer 1

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Neither ADO.NET nor SQL Server itself knows the number of rows before they have been sent. You can only find out by enumerating all rows.

Maybe you can just use a List instead of an array so that you don't have to pre-define the size?

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