網格視圖未顯示第一行ASP.NET，C＃SQL Server

Question

我試圖在網格視圖上顯示SQL表中的數據，但是，它不顯示數據的第一行，而是顯示隨后的數據行：這是我的代碼

public partial class DisplayGrid : System.Web.UI.Page
{
    string strConnString = System.Configuration.ConfigurationManager.ConnectionStrings["PostbankConnectionString"].ConnectionString;
    string query = "SELECT * FROM tbl_user";

    protected void Page_Load(object sender, EventArgs e)
    {
        //query 
        SqlConnection con = new SqlConnection(strConnString);
        SqlCommand cmd = new SqlCommand(query, con);
        cmd.CommandType = CommandType.Text;

        SqlDataReader reader;
        con.Open();
        reader = cmd.ExecuteReader();


        if (reader.Read())
        {
            GridView1.DataSource = reader;
            //Bind the data
            GridView1.DataBind();
        }

        reader.Close();
        con.Close();
    }
}

Answer 1

最好使用DataTable並通過DataTable.Load()加載SqlDataReader內容，而不是將閱讀器的內容直接分配給GridView實例：

DataTable dt = new DataTable();
using (SqlConnection con = new SqlConnection(strConnString))
{
    using (SqlCommand cmd = new SqlCommand(query, con))
    {
        cmd.CommandType = CommandType.Text;

        con.Open();
        SqlDataReader reader = cmd.ExecuteReader();

        if (reader.HasRows) // check if the reader contains rows
        {
            dt.Load(reader); // load to Datatable

            GridView1.DataSource = dt; // assign data source from DataTable
            GridView1.DataBind();
        }
    }
}

請注意， SqlDataReader是僅向前流 ，您需要使用DataTable或其他能夠執行反向和正向查找的集合。

Answer 2

刪除行if (reader.Read())因為DataReader.Read方法將SqlDataReader推進到下if (reader.Read())記錄。

這是代碼-

public partial class DisplayGrid : System.Web.UI.Page
{
    string strConnString = System.Configuration.ConfigurationManager.ConnectionStrings["PostbankConnectionString"].ConnectionString;
    string query = "SELECT * FROM tbl_user";

    protected void Page_Load(object sender, EventArgs e)
    {
        //query 
        SqlConnection con = new SqlConnection(strConnString);
        SqlCommand cmd = new SqlCommand(query, con);
        cmd.CommandType = CommandType.Text;

        SqlDataReader reader;
        con.Open();
        reader = cmd.ExecuteReader();
           GridView1.DataSource = reader;
           //Bind the data
            GridView1.DataBind();
            reader.Close();
        con.Close();
    }
}