'System.InvalidOperationException: 'Invalid attempt to read when no data is present.'-CodePudding

I am trying to connect tot he database and extract the contents, but whenever I try, I get this error:

System.InvalidOperationException: Invalid attempt to read when no data is present.

I'm not sure why no data is being read from the table, it seems to work perfectly fine when I connect to the other table I have in the database.

This is the code I use:

static void testcon()
{
    SqlConnection con = new SqlConnection(Programe.connectionString);
    con.Open();

    SqlCommand cmd1 = new SqlCommand("SELECT * FROM Auth WHERE Username = @username", con);
    cmd1.Parameters.AddWithValue("username", "test");

    SqlDataReader reader = cmd1.ExecuteReader();

    Console.WriteLine(reader[0]);

    con.Close();
}

The exception was thrown on this line of code:

Console.WriteLine(reader[0]);

This is the server explorer:

I have tried trying different key words in the SQL commands, different keywords in the method but I keep getting the same error.

I have tried

if (reader.read())
{
    //code here
}

but that wouldn't solve my issue as the data not being present would still occur

CodePudding user response：

try this.

You can print column name as per your need.

using (SqlDataReader reader = cmd1.ExecuteReader())
{
      while (reader.Read()) //The loop will run for all the rows in the result.
      {
          //loop on all the columns
          for (int i = 0; i < reader.FieldCount; i  )
          {
              Console.WriteLine(reader.GetValue(i));
          }
          Console.WriteLine();
       }
 }

CodePudding user response：

Try

while(reader.read())
{
// code here
}