将DataTable中的修改更新到数据库中

//前提：
        // 数据库aaa，有表bbb，字段为b varchar(10)
//代码如下：
   private void button1_Click(object sender, System.EventArgs e)
   {
    DataTable dt = (DataTable)this.dataGrid1.DataSource;

    System.Data.SqlClient.SqlConnection sqlConn = new SqlConnection("user id=sa;pwd=123;data source=(local);persist security info=False;initial catalog=aaa");
    System.Data.SqlClient.SqlCommand sqlCmd = new SqlCommand("select * from bbb",sqlConn);
    System.Data.SqlClient.SqlDataAdapter sqlAdap = new SqlDataAdapter(sqlCmd);

    System.Data.SqlClient.SqlCommandBuilder sqlBuild = new SqlCommandBuilder(sqlAdap);
    sqlConn.Open();
    sqlAdap.Update(dt);
    sqlConn.Close();
   }

   private void Form2_Load(object sender, System.EventArgs e)
   {

    DataTable dt = new DataTable();

    System.Data.SqlClient.SqlConnection sqlConn = new SqlConnection("user id=sa;pwd=123;data source=(local);persist security info=False;initial catalog=aaa");
    System.Data.SqlClient.SqlDataAdapter sqlAdap = new SqlDataAdapter("select * from bbb",sqlConn);

    sqlConn.Open();
    sqlAdap.Fill(dt);
    sqlConn.Close();

    this.dataGrid1.DataSource = dt;

   }