GetDataTable 问题

Question

   protected void Page_Load(object sender, EventArgs e)
    {
    }
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ETHANConnectionString"].ConnectionString);
        string a1 = DropDownList1.SelectedItem.Value.ToString();        string sql = "select PowerID from DEPARTMENT where Department='"+a1+"'";
        DataTable dt = new DataTable();
        dt = conn.GetDataTable(sql);
        if (dt.Rows.Count!=0)
        {
            TextBox1.Text = dt.Rows[0][0].ToString();
        }
        else { Response.Write("<script>alert('插入失败！')</script>"); }    }错误 5 “System.Data.SqlClient.SqlConnection”不包含“GetDataTable”的定义，并且找不到可接受类型为“System.Data.SqlClient.SqlConnection”的第一个参数的扩展方法“GetDataTable”(是否缺少 using 指令或程序集引用?)

Answer 1

conn.GetDataTable(sql);  SqlConnection没有你写的这个方法

Answer 2

 protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    { 
        string a1 = DropDownList1.SelectedItem.Value.ToString();
        string sql = "select PowerID from DEPARTMENT where Department='" + a1 + "'";
        DataTable dt = new DataTable();
        dt = ReturnDataTable(sql);
        if (dt.Rows.Count != 0)
        {
            TextBox1.Text = dt.Rows[0][0].ToString();
        }
        else { Response.Write("<script>alert('插入失败！')</script>"); }
    }
    public static DataTable ReturnDataTable(string cmdtext)
    {
        SqlConnection cn = new SqlConnection();
        cn.ConnectionString = ConfigurationManager.ConnectionStrings["ETHANConnectionString"].ConnectionString;
        DataTable dt = new DataTable();
        SqlCommand cmd = new SqlCommand();
        cmd = new SqlCommand(cmdtext, cn);
        cmd.CommandType = CommandType.Text; ;
        SqlDataReader dr = null;
        using (dr = cmd.ExecuteReader(CommandBehavior.CloseConnection))
        {
            dt.Load(dr);
        }
        return dt;
    }

Answer 3

噢
那我要是想达到
DROPDOWNLIST  选择 DepartmentN 
   TEXTBOX  获取 PowerID 该如何是好？

Answer 4

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ETHANConnectionString"].ConnectionString);
        string a1 = DropDownList1.SelectedItem.Value.ToString();        string sql = "select PowerID from DEPARTMENT where Department='"+a1+"'";
        SqlDataAdapter sda = new SqlDataAdapter(sql,conn);
        DataSet ds = new DataSet();
         sda.Fill(ds);
        if (ds.Tables[0].Rows.Count!=0)
        {
            TextBox1.Text =ds.Tables[0].Rows[0][0].ToString();
        }    }