SQL export to CSV file using .Net

Question

I have an app that saves a sql data set to a csv file. I read the data, loop each row saving into a string and then I save the string into a text file. The problem is there is a over 25k rows and it takes a long time to process. Is there a faster way to do this?

SqlDataAdapter sSQL2 = new SqlDataAdapter("SelUsersEmails", Conn);
DataSet RS2 = new DataSet();
sSQL2.Fill(RS2, "SelUsersEmails");


s = "UserID,SignUpDate,Email,PayPalEmail,Firstname,Lastname" + Environment.NewLine;



foreach (DataRow u in RS2.Tables["SelUsersEmails"].Rows)
{//loop each
        s += u["UserID"].ToString() + "," + u["SignUpDate"].ToString() + "," +["Email"].ToString() + "," + u["NetworkEmail"].ToString() + "," + ["Firstname"].ToString() + "," + u["Lastname"].ToString();

        s += Environment.NewLine;

}

Oded · Accepted Answer · 2012-02-14 21:31:46Z

1

There are many things that can be done - instead of string concatenation you can use StringBuilder to create it more efficiently.

Another option it to stream the data to the file as you go along - this is the most memory efficient way, though can be more IO intensive.

But I suggest using FileHelpers to create the CSV file. It is a popular library that is guaranteed to implement CSV properly (for example - what happens with your code if a field contains a comma?).

edited Feb 14, 2012 at 21:31

answered Feb 14, 2012 at 21:26

Oded

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Comments

cusimar9 · Accepted Answer · 2012-02-14 21:30:43Z

0

Why don't you open the file ready for writing and write each line as you're looping through the resultset?

That's the most efficient way of creating the CSV file.

answered Feb 14, 2012 at 21:30

cusimar9

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