Csharp/C Sharp/Database ADO.net/Table Column

Geting Table column data type

using System;
using System.Data;
using System.Data.OleDb;
public class DatabaseInfo {    
 public static void Main () { 
   String connect = "Provider=Microsoft.JET.OLEDB.4.0;data source=.\\Employee.mdb";
   OleDbConnection con = new OleDbConnection(connect);
   con.Open();  
   Console.WriteLine("Made the connection to the database");
   Console.WriteLine("Information for each table contains:");
   DataTable tables = con.GetOleDbSchemaTable(OleDbSchemaGuid.Tables,new object[]{null,null,null,"TABLE"});
   foreach(DataColumn col in tables.Columns) 
     Console.WriteLine("{0}\t{1}", col.ColumnName, col.DataType);
   con.Close();
 }
}

Read column values as C# types using the "Get" methods

using System;
using System.Data;
using System.Data.SqlClient;
class StronglyTypedColumnValues
{
  public static void Main()
  {
    SqlConnection mySqlConnection =new SqlConnection("server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI;");
    SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
    mySqlCommand.rumandText = "SELECT TOP 5 ProductID, ProductName, UnitPrice, " +
      "UnitsInStock, Discontinued " +
      "FROM Products " +
      "ORDER BY ProductID";
    mySqlConnection.Open();
    SqlDataReader productsSqlDataReader = mySqlCommand.ExecuteReader();
    int productIDColPos = productsSqlDataReader.GetOrdinal("ProductID");
    int productNameColPos = productsSqlDataReader.GetOrdinal("ProductName");
    int unitPriceColPos = productsSqlDataReader.GetOrdinal("UnitPrice");
    int unitsInStockColPos = productsSqlDataReader.GetOrdinal("UnitsInStock");
    int discontinuedColPos = productsSqlDataReader.GetOrdinal("Discontinued");
    Console.WriteLine("ProductID .NET type = " + productsSqlDataReader.GetFieldType(productIDColPos));
    Console.WriteLine("ProductName .NET type = " + productsSqlDataReader.GetFieldType(productNameColPos));
    Console.WriteLine("UnitPrice .NET type = " + productsSqlDataReader.GetFieldType(unitPriceColPos));
    Console.WriteLine("UnitsInStock .NET type = " + productsSqlDataReader.GetFieldType(unitsInStockColPos));
    Console.WriteLine("Discontinued .NET type = " + productsSqlDataReader.GetFieldType(discontinuedColPos));
    Console.WriteLine("ProductID database type = " + productsSqlDataReader.GetDataTypeName(productIDColPos));
    Console.WriteLine("ProductName database type = " + productsSqlDataReader.GetDataTypeName(productNameColPos));
    Console.WriteLine("UnitPrice database type = " + productsSqlDataReader.GetDataTypeName(unitPriceColPos));
    Console.WriteLine("UnitsInStock database type = " + productsSqlDataReader.GetDataTypeName(unitsInStockColPos));
    Console.WriteLine("Discontinued database type = " + productsSqlDataReader.GetDataTypeName(discontinuedColPos));
    while (productsSqlDataReader.Read())
    {
      int productID = productsSqlDataReader.GetInt32(productIDColPos);
      Console.WriteLine("productID = " + productID);
      string productName = productsSqlDataReader.GetString(productNameColPos);
      Console.WriteLine("productName = " + productName);
      decimal unitPrice = productsSqlDataReader.GetDecimal(unitPriceColPos);
      Console.WriteLine("unitPrice = " + unitPrice);
      short unitsInStock = productsSqlDataReader.GetInt16(unitsInStockColPos);
      Console.WriteLine("unitsInStock = " + unitsInStock);
      bool discontinued = productsSqlDataReader.GetBoolean(discontinuedColPos);
      Console.WriteLine("discontinued = " + discontinued);
    }
    productsSqlDataReader.Close();
    mySqlConnection.Close();
  }
}

Read column values as Sql* types using the GetSql* methods

using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
class StronglyTypedColumnValuesSql
{
  public static void Main()
  {
    SqlConnection mySqlConnection =new SqlConnection("server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI;");
    SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
    mySqlCommand.rumandText =
       "SELECT TOP 5 ID, Name, UnitPrice, " +
       "UnitsInStock, Discontinued " +
       "FROM Products " +
       "ORDER BY ProductID";
    mySqlConnection.Open();
    SqlDataReader productsSqlDataReader = mySqlCommand.ExecuteReader();
    int productIDColPos = productsSqlDataReader.GetOrdinal("ID");
    int productNameColPos = productsSqlDataReader.GetOrdinal("Name");
    int unitPriceColPos = productsSqlDataReader.GetOrdinal("UnitPrice");
    int unitsInStockColPos = productsSqlDataReader.GetOrdinal("UnitsInStock");
    int discontinuedColPos = productsSqlDataReader.GetOrdinal("Discontinued");
    while (productsSqlDataReader.Read())
    {
      SqlInt32 productID = productsSqlDataReader.GetSqlInt32(productIDColPos);
      Console.WriteLine("productID = " + productID);
      SqlString productName = productsSqlDataReader.GetSqlString(productNameColPos);
      Console.WriteLine("productName = " + productName);
      SqlMoney unitPrice = productsSqlDataReader.GetSqlMoney(unitPriceColPos);
      Console.WriteLine("unitPrice = " + unitPrice);
      SqlInt16 unitsInStock = productsSqlDataReader.GetSqlInt16(unitsInStockColPos);
      Console.WriteLine("unitsInStock = " + unitsInStock);
      SqlBoolean discontinued = productsSqlDataReader.GetSqlBoolean(discontinuedColPos);
      Console.WriteLine("discontinued = " + discontinued);
    }
    productsSqlDataReader.Close();
    mySqlConnection.Close();
  }
}

Refernece column name in SqlDataReader

using System;
using System.Data.SqlClient;
class FirstExample
{
  public static void Main()
  {
    try
    {
      SqlConnection mySqlConnection = new SqlConnection("server=(local)\\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI");
      SqlCommand mySqlCommand = mySqlConnection.CreateCommand();
      mySqlCommand.rumandText =  "SELECT id, firstname, lastname from employee";
      mySqlConnection.Open();
      SqlDataReader mySqlDataReader = mySqlCommand.ExecuteReader();
      mySqlDataReader.Read();
      Console.WriteLine("mySqlDataReader[\" ID\"] = "+ mySqlDataReader["ID"]);
      Console.WriteLine("mySqlDataReader[\" First Name\"] = "+ mySqlDataReader["FirstName"]);
      Console.WriteLine("mySqlDataReader[\" Last Name\"] = "+ mySqlDataReader["LastName"]);
      mySqlDataReader.Close();
      mySqlConnection.Close();
    }
    catch (SqlException e)
    {
      Console.WriteLine("A SqlException was thrown");
      Console.WriteLine("Number = "+ e.Number);
      Console.WriteLine("Message = "+ e.Message);
      Console.WriteLine("StackTrace:\n" + e.StackTrace);
    }
  }
}