Working with SQL and Oracle Connection to Bind Values in ASP.NET

Introduction
 
Below are some examples for Working with SQL and Oracle connection to bind data to dropdown and retreive values from datatable in asp.net.

Bind output of Oracle query to dropdown

OracleConnection conn = new OracleConnection();conn.ConnectionString = ConfigurationManager.ConnectionStrings["Conne
tionString"
].ConnectionString;

OracleCommand
cmd = new OracleCommand("SELECT EMPLOYEE_ID ID, EMPLOYEE_NAME VALUE FROM EMPLOYEE MASTER",
conn);

OracleDataAdapter
oda = new OracleDataAdapter(cmd);
DataSet
ds = new DataSet();
oda.Fill(ds);
Dropdown.DataSource = ds;
Dropdown.DataTextField = "VALUE";
Dropdown.DataValueField = "ID";
Dropdown.DataBind();

Retrieving Datatable as an output from Oracle query

protected
virtual DataTable ConnectAndQuery()
{
    OracleConnection conn = new OracleConnection();
    conn.ConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
    conn.Open();
    OracleCommand command = conn.CreateCommand();
    string sql = "SELECT EMPLOYEE_ID ID, EMPLOYEE_NAME VALUE FROM EMPLOYEE MASTER";
    command.CommandText = sql;

    OracleDataReader
reader = command.ExecuteReader();

    DataTable
dtusertables = new DataTable();

    dtusertables.Load(reader);

    if
(null != reader && !reader.IsClosed)

    {

        reader.Close();

    }

    return
dtusertables;

}
 
Bind output of Sql query to dropdown

SqlConnection
conn = new SqlConnection("ConnectionString");
SqlCommand
cmd = new SqlCommand();
cmd.CommandText = "SELECT EMPLOYEE_ID ID, EMPLOYEE_NAME VALUE FROM EMPLOYEE MASTER";

cmd.Connection = conn;
conn.Open();
DataTable
dt = new DataTable();
dt.Load(cmd.ExecuteReader());
conn.Close();
Dropdown.DataSource = dt;
Dropdown.DataTextField = "VALUE";
Dropdown.DataValueField = "ID";
Dropdown.DataBind();

Retrieving Datatable as an output from Sql query

protected virtual DataTable ConnectAndQuery()
{

    string
sql = "SELECT EMPLOYEE_ID ID, EMPLOYEE_NAME VALUE FROM EMPLOYEE MASTER";

    using
(SqlConnection conn = new SqlConnection("ConnectionString"))
    {
         using (SqlCommand cmd = new SqlCommand(sql, conn))
        {
            conn.Open();

            using
(SqlDataReader reader = cmd.ExecuteReader())

            {
                  DataTable dt = new DataTable();
                  dt.Load(reader);
                  conn.Close();
                  return
dt;
            }
        }
 }