// Namespaces, variables, and constants
using System;
using System.Configuration;
using System.Text;
using System.Data;
using System.Data.SqlClient;

//  . . . 

StringBuilder result = new StringBuilder( );

// Fill the Orders table with schema and data.
SqlDataAdapter da = new SqlDataAdapter("SELECT * FROM Orders",
    ConfigurationSettings.AppSettings["Sql_ConnectString"]);
DataTable ordersTable = new DataTable(ORDERS_TABLE);
da.FillSchema(ordersTable, SchemaType.Source);
da.Fill(ordersTable);

SqlConnection conn = new SqlConnection(
    ConfigurationSettings.AppSettings["Sql_ConnectString"]);

// Command for system stored procedure returning constraints
SqlCommand cmd = new SqlCommand("sp_helpconstraint", conn);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add("@objname",SqlDbType.NVarChar,776);
cmd.Parameters[0].Value = "Orders";
cmd.Parameters.Add("@nomsg",SqlDbType.VarChar,5);
cmd.Parameters[1].Value = "nomsg";

// Create a DataReader from the stored procedure.
conn.Open( );
SqlDataReader dr = cmd.ExecuteReader( );

// Iterate over the constraints records in the DataReader.
while(dr.Read( ))
{
    // Select the default value constraints only.
    String constraintType = dr["constraint_type"].ToString( );
    if (constraintType.StartsWith("DEFAULT"))
    {
        String constraintKeys = dr["constraint_keys"].ToString( );
        // Only strips single quotes for numeric default types
        // add necessary handling as required for nonnumeric defaults
        String defaultValue =
            constraintKeys.Substring(1, constraintKeys.Length - 2);

        String colName = constraintType.Substring(
            (constraintType.LastIndexOf("column") + 7));

        ordersTable.Columns[colName].DefaultValue = defaultValue;

        result.Append("Column: " + colName + "   Default: " +
            defaultValue + Environment.NewLine);
    }
}
dr.Close( );
conn.Close( );

resultTextBox.Text = result.ToString( );