Connect to SQL Server Database using SqlDataReader

แบบที่ 1

SqlConnection conn = new SqlConnection("Data Source=.\\sqlexpress;Initial Catalog=Northwind;Integrated Security=true");
SqlCommand cmd = new SqlCommand("SELECT * FROM [Categories]",conn);
SqlDataReader rdr = null;

try
{
conn.Open();
rdr = cmd.ExecuteReader();
while(rdr.Read())
{
Response.Write(rdr["CategoryID"] + " " + rdr["CategoryName"] + " " + rdr["Description"] + "<br/>");
}
}
catch(Exception ex)
{
Response.Write("Error!! " + ex.Message);
}
finally
{
if(rdr != null)
rdr.Close();
if(conn.State == ConnectionState.Open)
conn.Close();
}

แบบที่ 2

using (SqlConnection conn = new SqlConnection("Data Source=.\\sqlexpress;Initial Catalog=Northwind;Integrated Security=true"))
{
try
{
SqlCommand cmd = new SqlCommand("SELECT * FROM [Categories]", conn);
SqlDataReader rdr = null;
conn.Open();
rdr = cmd.ExecuteReader();
while (rdr.Read())
{
Response.Write(rdr["CategoryID"] + " " + rdr["CategoryName"] + " " + rdr["Description"] + "<br/>");
}
}
catch (Exception ex)
{
Response.Write("Error!! " + ex.Message);
}
}