[ACCEPTED]-How do I connect to a database and loop over a recordset in C#?-connection

@Goyuix -- that's excellent for something 3 written from memory. tested it here -- found 2 the connection wasn't opened. Otherwise 1 very nice.

using System.Data.OleDb;
...

using (OleDbConnection conn = new OleDbConnection())
{
    conn.ConnectionString = "Provider=sqloledb;Data Source=yourServername\\yourInstance;Initial Catalog=databaseName;Integrated Security=SSPI;";

    using (OleDbCommand cmd = new OleDbCommand())
    {
        conn.Open();
        cmd.Connection = conn;
        cmd.CommandText = "Select * from yourTable";

        using (OleDbDataReader dr = cmd.ExecuteReader())
        {
            while (dr.Read())
            {
                Console.WriteLine(dr["columnName"]);
            }
        }
    }
}

Very roughly and from memory since I don't 1 have code on this laptop:

using (OleDBConnection conn = new OleDbConnection())
{
  conn.ConnectionString = "Whatever connection string";

  using (OleDbCommand cmd = new OleDbCommand())
  {
    cmd.Connection = conn;
    cmd.CommandText = "Select * from CoolTable";

    using (OleDbDataReader dr = cmd.ExecuteReader())
    {
      while (dr.Read())
      {
        // do something like Console.WriteLine(dr["column name"] as String);
      }
    }
  }
}

That's definitely a good way to do it. But 3 you if you happen to be using a database 2 that supports LINQ to SQL, it can be a lot 1 more fun. It can look something like this:

MyDB db = new MyDB("Data Source=...");
var q = from db.MyTable
        select c;
foreach (var c in q)
  Console.WriteLine(c.MyField.ToString());

This is an alternative way (DataReader is 1 faster than this one):

string s = "";
SqlConnection conn = new SqlConnection("Server=192.168.1.1;Database=master;Connect Timeout=30;User ID=foobar;Password=raboof;");
SqlDataAdapter da = new SqlDataAdapter("SELECT TOP 5 name, dbid FROM sysdatabases", conn);
DataTable dt = new DataTable();

da.Fill(dt);

for (int i = 0; i < dt.Rows.Count; i++)
{
    s += dt.Rows[i]["name"].ToString() + " -- " + dt.Rows[i]["dbid"].ToString() + "\n";
}

MessageBox.Show(s);

If you are querying a SQL Server database 8 (Version 7 and up) you should replace the 7 OleDb classes with corresponding classes 6 in the System.Data.SqlClient namespace (SqlConnection, SqlCommand and SqlDataReader) as those classes 5 have been optimized to work with SQL Server.

Another 4 thing to note is that you should 'never' select 3 all as this might lead to unexpected results 2 later on if you add or remove columns to 1 this table.

If you are intending on reading a large 3 number of columns or records it's also worth 2 caching the ordinals and accessing the strongly-typed 1 methods, e.g.

using (DbDataReader dr = cmd.ExecuteReader()) {
  if (dr.Read()) {
    int idxColumnName = dr.GetOrdinal("columnName");
    int idxSomethingElse = dr.GetOrdinal("somethingElse");

    do {
      Console.WriteLine(dr.GetString(idxColumnName));
      Console.WriteLine(dr.GetInt32(idxSomethingElse));
    } while (dr.Read());
  }
}

I guess, you can try entity framework.

using (SchoolDBEntities ctx = new SchoolDBEntities())
{
     IList<Course> courseList = ctx.GetCoursesByStudentId(1).ToList<Course>();
     //do something with courselist here
}

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Charge the libraries

using MySql.Data.MySqlClient;

This is the connection:

public static MySqlConnection obtenerconexion()
{
    string server = "Server";
    string database = "Name_Database";
    string Uid = "User";
    string pwd = "Password";
    MySqlConnection conect = new MySqlConnection("server = " + server + ";" + "database =" + database + ";" + "Uid =" + Uid + ";" + "pwd=" + pwd + ";");

    try
    {
        conect.Open();
        return conect;
    }
    catch (Exception)
    {
        MessageBox.Show("Error. Ask the administrator", "An error has occurred while trying to connect to the system", MessageBoxButtons.OK, MessageBoxIcon.Error);
        return conect;
    }
}

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