//引用这两个命名空间
using System.Data.SqlClient;
using System.Data;
// 初始化连接对象
SqlConnection conn = new SqlConnection();
conn.ConnectionString = "User ID=sa;Initial Catalog=DataBaseName;Data Source= (local);Password=111111";
// 打开连接
if (conn.State == ConnectionState.Closed)
{
  conn.Open();
}
// 初始化命令
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandType = CommandType.Text;
cmd.CommandText = "sql语句";
// 用于执行数据插入、更新和删除的操作；返回被影响的行数。
int i = cmd.ExecuteNonQuery();
if(i>0){MessageBox.Show("操作成功");}
// 用于查询最大值等只需返回一条数据情况下的操作；返回的是首行第一列的数据。
object obj = cmd.ExecuteScalar();
// 如果想获取数据集合的话我们经常使用到的是数据适配器
DataTable dt = new DataTable();
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.SelectCommand = cmd;
adapter.Fill(dt);

string str = "Data Source=.;Initial Catalog=GridView;User ID=sa;Password=111111";
string sql = "select * from UserName";
SqlConnection conn = new SqlConnection(str);
//conn.Open(); 使用 SqlDataAdapter（数据适配器）不用写
//SqlCommand comm = new SqlCommand(sql, conn);
//SqlDataAdapter dr = new SqlDataAdapter(comm);
SqlDataAdapter dr = new SqlDataAdapter(sql,conn);//上面两句可以合并成这一
DataSet ds = new DataSet();//创建数据集；
dr.Fill(ds); //填充数据集
this.GridView1.DataSource = ds;
this.GridView1.DataBind();//讲数据源绑定到控件上，
//conn.Close(); 关闭数据库连接
if (conn.State==ConnectionState.Open) //判断数据库连接状态，是否连接
{
conn.Close();
}

string str = "Data Source=.;Initial Catalog=GridView;User ID=sa;Password=111111";
string sql = "select * from UserName";
SqlConnection conn = new SqlConnection(str);
conn.Open();
SqlCommand comm = new SqlCommand(sql, conn);
DataSet ds = new DataSet();
SqlDataReader dr = comm.ExecuteReader();
if (dr.Read())
{
  //下面两种都可以获得数据
  //this.TextBox1.Text = dr.GetString(1);
  //this.TextBox2.Text = dr.GetInt32(3).ToString();
  this.TextBox1.Text = dr.GetString(dr.GetOrdinal("Name"));
  this.TextBox2.Text = dr.GetInt32(dr.GetOrdinal("Age")).ToString();
}
//循环输出
while (dr.Read())
{
  Response.Write(dr["Name"]);
  Response.Write(dr["Age"]);
  Response.Write("<br/>");
}
dr.Close();
if (conn.State == ConnectionState.Open)
{
  conn.Close();
}

PropertyName1=Value1;
PropertyName2=Value2;
PropertyName3=Value3;
.....