CODEWITHSUNDEEP
c#.netado.netoledb
Mikey
Mikey

Reputation: 69

C# OleDbCommand Connection Properties

I wonder why this code didnt work since I already build a method to connect to the database and open the connection. I assume this is because I skip the use of the OleDbCommand Connection properties. Is it mandatory to use this properties?

My attempt to assign the Connection() method directly to the OleDbCommand cmd = new OleDbCommand("SELECT City FROM Employees", Connection().Open()); object also didnt work.

using System;
using System.Data;
using System.Data.OleDb;

class KDRM
{
static void Main()
{

    OleDbCommand cmd = new OleDbCommand("SELECT City FROM Employees");
    Connection().Open();
    OleDbDataReader rdr = cmd.ExecuteReader();


    while (rdr.Read())
    {

        Console.WriteLine(rdr.GetString(0));
    }

    Console.ReadLine();
}

public static OleDbConnection Connection()
{       
    OleDbConnection conn = new OleDbConnection();
    conn.ConnectionString = "Connection...";

    return conn;
}


}

Upvotes: 2

Views: 486

Answers (2)

Steve
Steve

Reputation: 216293

This line

OleDbCommand cmd = new OleDbCommand("SELECT City FROM Employees", Connection().Open());

could not work because you are trying to pass the result of Open as second parameter of the OleDbCommand constructor, but this is a void method so your code doesn't even compile.

Whenever you try to execute a command, you need to set the command connection property, to a valid connection and that connection should be open at the moment in which you execute the command.

There are established good practices to use when creating a connection and you should follow it for a good reason

static void Main()
{

    using(OleDbConnection cn = Connection())
    using(OleDbCommand cmd = new OleDbCommand("SELECT City FROM Employees", cn);
    {
         cn.Open();
         using(OleDbDataReader rdr = cmd.ExecuteReader())
         {
             while (rdr.Read())
             {
                ....
             }
         }
    }
    Console.ReadLine();

}

The using statement ensures that the disposable objects in your code are closed and disposed also in case of exceptions.

Upvotes: 2

Boris Sokolov
Boris Sokolov

Reputation: 1793

You should add this kind of code:

// Set the Connection to the new OleDbConnection.
command.Connection = connection;

reference

Upvotes: 1

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