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POGetting exception: Invalid attempt to read when reader is closed
 

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  1. POGetting exception: Invalid attempt to read when reader is closed
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    <p>I am attempting to read a MySQL database from my C# project using the MySQL drivers for .net off the MySQL site.</p> <p>Though I did a bit of research on this (including <a href="https://stackoverflow.com/questions/5516914/invalid-attempt-to-read-when-reader-is-closed">this</a>), I am still flummoxed why this is happening. I later ran a spike and I still get the same error. (Prior to running this I populated the database with some default values.) Here's the spike code in toto.</p> <pre><code>class Program { static void Main (string[] args) { Console.WriteLine (GetUserAge ("john")); // o/p's -1 } static int GetUserAge (string username) { string sql = "select age from users where name=@username"; int val = -1; try { using (MySqlConnection cnn = GetConnectionForReading ()) { cnn.Open (); MySqlCommand myCommand = new MySqlCommand (sql, cnn); myCommand.Parameters.AddWithValue ("@username", username); using (MySqlDataReader reader = myCommand.ExecuteReader ()) { DataTable dt = new DataTable (); dt.Load (reader); if (reader.Read ()) { val = reader.GetInt32 (0); } } } } catch (Exception ex) { Console.WriteLine (ex.Message); } finally { } return val; } private static MySqlConnection GetConnectionForReading () { string conStr = "Data Source=localhost;Database=MyTestDB;User ID=testuser;Password=password"; return new MySqlConnection (conStr); } } </code></pre> <p>The code above gives me the exception: "Invalid attempt to Read when reader is closed."</p> <p>Later I modified the if-condition like so:</p> <pre><code>if (reader.HasRows &amp;&amp; reader.Read ()) { val = reader.GetInt32 (0); } </code></pre> <p>And now the o/p is -1. (The data's in there in the table.) If for some reason the result set had zero rows, the reader should not have got into the if-block in the first place. I mean, the whole point of the Read() method is to check if there are any rows in the result set in the first place.</p> <p>At my wit's end here... just cannot figure out where I'm going wrong.</p> <p>Thank you for your help! :)</p>
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    1. CO@harpo: You should make that comment an answer
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    2. CO@BrokenGlass, okay, was just using etiquette for off-the-top-of-my-head :)
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    3. COSame error in a different scenario http://stackoverflow.com/questions/6775136/invalid-attempt-to-call-read-when-reader-is-closed-error-for-lengthy-operatio
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