下拉框刷数据源 DAtatable

private void Form1_Load(object sender, EventArgs e)
        {
            string connstr = "server=(local);uid=sa;pwd=ccxx;database=master";
            string sql = "select id,班级 from 班级1";
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                try
                {
                    SqlCommand com = new SqlCommand();
                    SqlDataAdapter da = new SqlDataAdapter(sql, conn);

                    DataTable dt = new DataTable();
                    da.SelectCommand = com;
                    da.SelectCommand.CommandType = CommandType.Text;
                    da.SelectCommand.CommandText = sql;
                    da.Fill(dt);    comboBox1.DataSource = dt;
                    comboBox1.DisplayMember ="班级";
                    comboBox1.ValueMember = "id";

                }
                catch (Exception ex)
                {

                    //throw (new SqlException(ex.Message));
                }

数据刷不出来不知道怎么了  高人指点  要求必须用datatable因为我练习这个  dataset我已经会了
--------------------编程问答--------------------



        private void Form1_Load(object sender, EventArgs e) 

        { 

            string connstr = "server=(local);uid=sa;pwd=ccxx;database=master"; 

            string sql = "select id,班级 from 班级1"; 

            using (SqlConnection conn = new SqlConnection(connstr)) 

            { 

                //conn.Open(); 

                try 

                { 

                    //SqlCommand com = new SqlCommand(); 

                    SqlDataAdapter da = new SqlDataAdapter(sql, conn); 



                    DataTable dt = new DataTable(); 

                    //da.SelectCommand = com; 

                    //da.SelectCommand.CommandType = CommandType.Text; 

                    //da.SelectCommand.CommandText = sql; 

                    da.Fill(dt);    comboBox1.DataSource = dt; 

                    comboBox1.DisplayMember ="班级"; 

                    comboBox1.ValueMember = "id"; 





                } 

                catch (Exception ex) 

                { 



                    //throw (new SqlException(ex.Message)); 

                }

改成上面的，你再试试看？
--------------------编程问答--------------------
                    conn.Open();
                    SqlCommand com = new SqlCommand();
                    SqlDataAdapter da = new SqlDataAdapter();

                    DataTable dt = new DataTable();

                    com.CommandType = CommandType.Text;
                    com.CommandText = sql;
                    com.Connection = conn;
                    da.SelectCommand = com;

                    da.Fill(dt);

                   // DataSet ds = new DataSet();

                    //da.Fill(ds, "table");

                    comboBox1.DataSource = dt;
                    comboBox1.DisplayMember ="班级";
                    comboBox1.ValueMember = "id";

这样也可以你的也可以谢谢啦  结贴
--------------------编程问答-------------------- 学习~ --------------------编程问答-------------------- 如果你是用在后面刷新的话，建议你把他封装成一个方法好点，这样你要用的话直接调用就可以了！

补充：.NET技术 ,  C#