System.Data.SqlClient.SqlConnection cnn = new System.Data.SqlClient.SqlConnection("连接字符串");
System.Data.SqlClient.SqlCommand cm = new System.Data.SqlClient.SqlCommand();
cm.Connection = cnn;
cm.CommandText = sql;
cm.Parameters.Add("@par");
cm.Parameters["@par"].Value = this.TextBox1.Text;
System.Data.SqlClient.SqlDataAdapter da = new System.Data.SqlClient.SqlDataAdapter(cm);