error 'there is already an open datareader associated with this command which must be closed first'

Question

runtime error \'there is already an open datareader associated with this command which must be closed first\'

objCommand = new SqlCommand(\"SELECT field1, fi         


        

Answer 1

Option 1: Must execute query and load data before running another query.

Option 2: Add MultipleActiveResultSets=true to the provider part of your connection string. See the example below:

<add name="DbContext" connectionString="Data Source=(LocalDb)\v11.0;Initial Catalog=dbName;Persist Security Info=True;User ID=userName;Password=password;MultipleActiveResultSets=True" providerName="System.Data.SqlClient" />

Answer 2

Best Solution: There is only problem with your "CommandText" value. Let it be SP or normal Sql Query.

• Check 1: The parameter value which you are passing in your Sql Query is not changing and going same again and again in your ExecuteReader.

• Check 2: Sql Query string is wrongly formed.

• Check 3: Please create simplest code as follows.

  string ID = "C8CA7EE2";
  string myQuery = "select * from ContactBase where contactid=" + "'" + ID + "'";
  string connectionString = ConfigurationManager.ConnectionStrings["CRM_SQL_CONN_UAT"].ToString(); 
  SqlConnection con = new SqlConnection(connectionString);
  con.Open();
  SqlCommand cmd = new SqlCommand(myQuery, con);
  DataTable dt = new DataTable();
  dt.Load(cmd.ExecuteReader());
  con.Close();
  

Answer 3

Try something like this:

//Add a second connection based on the first one
SqlConnection objConn2= new SqlConnection(objConn.connectionString))

SqlCommand objInsertCommand= new SqlCommand();
objInsertCommand.CommandType = CommandType.Text;
objInsertCommand.Connection = objConn2;

while (objDataReader.Read())
{
    objInsertCommand.CommandText = "INSERT INTO tablename (field1, field2) VALUES (3, '" + objDataReader[0] + "')";
    objInsertCommand.ExecuteNonQuery();
}

Answer 4

No need to do all that, just turn on MARS and your problem will get solved. In your connection string just add MultipleActiveResultSets=True;

Answer 5

You can't perform an action on that connection while it's still working on reading the contents of a data reader - the error is pretty descriptive.

Your alternatives are:

1) Retrieve all your data first, either with a DataSet or use the reader to populate some other collection, then run them all at once after the initial select is done.

2) Use a different connection for your insert statements.

Answer 6

In order for it to be disposed easily i use the following coding-template :

`using (SqlConnection connection = new SqlConnection("your connection string"))
        {
            connection.Open();
            using (SqlCommand cmd = connection.CreateCommand())
            {
                cmd.CommandText = "Select * from SomeTable";
                using (SqlDataReader reader = cmd.ExecuteReader())
                {

                    if(reader.HasRows)
                    { 
                       while(reader.Read()){
                       // assuming that we've a 1-column(Id) table 
                       int id = int.Parse(reader[0].ToString()); 

                       }
                    }
                }
            } 
            connection.Close()
        }`