在查询中将数据类型nvarchar转换为数值时出错

Question

I want to call the ID of the row because I want to delete the row.

Here is my code:-

private void DeleteAttachment(string ID)
{
    using (SqlConnection connection = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["ConnectionString"].ToString()))
    {
        connection.Open();
        string sql = "DELETE FROM EMP_ATTACHED_DOCUMENTS WHERE mkey= @ID";
        using (SqlCommand cmd = new SqlCommand(sql, connection))
        {
            cmd.Parameters.AddWithValue("@ID", ID);
            cmd.CommandType = CommandType.Text;
            cmd.ExecuteNonQuery();
        }
    }
}

protected void GrdTraining_DeleteCommand(object sender, Obout.Grid.GridRecordEventArgs e)
{
    if (Session["dt10"] != null)
    {
        dt10 = (DataTable)Session["dt10"];
    }
    else
    {
        BindDatatable();
    }
    DeleteAttachment(ID);

    DataRow[] grdTrain = dt10.Select("SR_NO=" + Convert.ToString(e.Record["SR_NO"]));
    dt10.Rows.Remove(grdTrain[0]);
    AddToViewState("GrdTraining");
}

but I am unable to delete the row. When I tried to debug it, at ID , I was getting _Page .

The error message:

Error converting data type nvarchar to numeric

Please, suggest a way to call a dynamic ID.

Answer 1

Based on your comments I think you need to do something like the following

private void DeleteAttachment(string ID)
{
    decimal numericId;
    if(!decimal.TryParse(ID, out numericId))
    {
        // The ID is not a valid decimal determine what to do in that case.
    }

    using (SqlConnection connection = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["ConnectionString"].ToString()))
    {
        connection.Open();
        string sql = "DELETE FROM EMP_ATTACHED_DOCUMENTS WHERE mkey= @ID";
        using (SqlCommand cmd = new SqlCommand(sql, connection))
        {
            cmd.Parameters.Add("@ID", SqlDbType.Decimal).Value = numericId;
            cmd.CommandType = CommandType.Text;
            cmd.ExecuteNonQuery();
        }
    }
}

Alternatively you could change the ID argument to the DeleteAttachment method to be a decimal and do the parsing outside the method.

Answer 2

within the DeleteAttachment I would simply put:

decimal temp;
if (!Decimal.TryParse(ID, out temp)) { return; }