Question

我在尝试从下拉列表中选择日期时遇到此错误，一旦选择了日期，它应该根据下拉列表值在GridView中显示数据。这是使用'Where'语句等于所选索引的值来实现的。

我知道日期显示在下拉列表中的方式存在问题，而不是它们在数据库中保存的方式。所以我试图在下拉列表中将格式从dd / mm / yyyy交换到yyyy / mm / dd，看看是否能解决问题。但我似乎无法让它发挥作用。

有人可以推荐修复此问题吗？

下拉列表选择的索引更改C＃：

protected void DropDownList2_SelectedIndexChanged(object sener, EventArgs e)
    {
        String query = "SELECT Stock_Take.Username, Item.ItemID, Item.ItemDesc, Stock_Take_Item.BarQuantity, Stock_Take_Item.StorageQuantity, Stock_Take.StockTakeIDNew FROM Item INNER JOIN Stock_Take_Item ON Item.ItemID = Stock_Take_Item.ItemID INNER JOIN Stock_Take ON Stock_Take_Item.StockTakeIDNew = Stock_Take.StockTakeIDNew where Stock_Take.Username = @USER AND Stock_Take.StockDate = @DATE";

        SqlConnection con = new SqlConnection(@"Data Source=(local)\;Initial Catalog=SmallBatch;Integrated Security=True;");
        con.Open();
        SqlCommand cmd = new SqlCommand(query, con);

        cmd.Parameters.Add("@USER", SqlDbType.VarChar).Value = DropDownList1.SelectedValue;
        cmd.Parameters.Add("@DATE", SqlDbType.DateTime).Value = DropDownList2.SelectedValue;
       // DateTime date = Convert.ToDateTime(DropDownList2.SelectedValue.ToString());
        SqlDataReader reader = cmd.ExecuteReader();
        GridView1.DataSource = reader;
        GridView1.DataBind();
        con.Close();


    }

将日期从数据库绑定到下拉列表C＃代码：

private void BindDropDownList2(String field)
    {
        DataTable dataTable = new DataTable();
        SqlConnection con = new SqlConnection(@"Data Source=(local)\;Initial Catalog=SmallBatch;Integrated Security=True;");
        try
        {
            con.Open();
            String Query = "Select StockDate, StockTakeIDNEW from Stock_Take WHERE Username = @Value1";
            SqlCommand sqlCmd = new SqlCommand(Query, con);
            sqlCmd.Parameters.AddWithValue("@Value1", field);

            SqlDataAdapter sqlDa = new SqlDataAdapter(sqlCmd);
            sqlDa.Fill(dataTable);
            if (dataTable.Rows.Count > 0)
            {
                DropDownList2.DataSource = dataTable;
                DropDownList2.DataTextField = "StockDate";
                DropDownList2.DataValueField = "StockTakeIDNew";
               // DropDownList2.DataTextFormatString = "(yyyy/MM/dd}";
                DropDownList2.DataBind();
            }

        }
        catch (System.Data.SqlClient.SqlException ex)
        {
            string msg = "Fetch Error";
            msg += ex.Message;

*我还有另一个下拉列表，用户从中选择一个用户名，进而影响DropDownList2中显示的日期

Answer 1

下面：

cmd.Parameters.Add("@DATE", SqlDbType.DateTime).Value = DropDownList2.SelectedValue;

首先手动解析值，因此它是DateTime：

var date = DateTime.Parse(DropDownList2.SelectedValue); // TODO: replace with format etc
cmd.Parameters.Add("@DATE", SqlDbType.DateTime).Value = date;

'无法将参数值从字符串转换为日期时间'

1 个答案: