Question

我知道这是一个重复的问题，但我已经尝试了很多，但我得到了异常

$ exception {＆＃34; String未被识别为有效的DateTime。＆＃34;} System.Exception {System.FormatException}

以下是我的代码，请查看并指导

SQL QUERY

SELECT gangId as gang，respectPoints as respectPoints，DATE_FORMAT（purchaseDate，＆＃39;％d-％m-％Y＆＃39;）as date_purchase FROM tbl_gang t其中gangId =＆＃34; + gangId

数据访问层代码

DataTable dt = new DataTable();
MySqlCommand cmd = conn.CreateCommand();
MySqlDataAdapter da = new MySqlDataAdapter(cmd);
cmd.CommandText = inAppPurchaseQuery;
da.Fill(dt)

排序代码

dt = gangRPObj.getGangRPLogsBL(gangId, fromDate, toDate);
var sortedTable = dt.AsEnumerable()
             .OrderBy(r => DateTime.ParseExact(("date_purchase"),
                                                "dd-mm-yyyy", null))
             .CopyToDataTable();

由于

Answer 1

您正在将字符串传递给日期时间转换，这就是异常即将发生的原因。试试

var orderedRows = from row in dt.AsEnumerable()
                  let date = DateTime.ParseExact(row.Field<string>("date_purchase"),"dd-mm-yyyy", null)
                  orderby date 
                  select row;

Answer 2

将日期列排序为字符串也无法正确排序。您还应该在数据库中而不是在内存中进行排序，并使用参数而不是字符串连接来防止sql-injection和date-conversion-issues这样的问题。

string sql = @"SELECT gangId as gang, 
                      respectPoints as respectPoints, 
                      DATE_FORMAT(purchasedDate, '%d-%m-%Y') as date_purchase,
               FROM tbl_gang t 
               WHERE gangId=@gangId
               ORDER BY purchasedDate ASC";
using (var cmd = new MySqlCommand(sql, conn))
using (var da = new MySqlDataAdapter(cmd))
{
    da.SelectCommand.Parameters.Add("@gangId", MySql.Data.MySqlClient.MySqlDbType.Int32).Value = gangID;
    da.Fill(dt);  // no need to order this on client side
}

C＃：使用列日期对DATATABLE进行排序

2 个答案: