Question

我需要清理一个填充了重复值的数据库，我想删除所有重复的旧日期。目的：

- 如果序列ID有＆gt; 1个条目，删除除最新日期之外的所有日期

Asset_Table （显示所有重复的Serial_ID）

    Serial_ID       |    ISSI     |     Date_Added
---------------------------------------------------------
 2PND00849EWS8J1    |   3766040   |  2012-07-06 08:52:23.000
 2PND00849EWS8J1    |   3778051   |  2016-09-26 09:21:57.000

预期结果：

   Serial_ID        |    ISSI     |     Date_Added
---------------------------------------------------------
 2PND00849EWS8J1    |   3778051   |  2016-09-26 09:21:57.000

Answer 1

使用@model IEnumerable<OnlineTaxiReservationSystem.Models.Comment> <p> @Html.ActionLink("Create New", "Create") </p> <table class="table"> <tr> <th> @Html.DisplayNameFor(model => model.UserComments) </th> @*<th> @Html.DisplayNameFor(model => model.UserId) </th>*@ <th></th> </tr> @foreach (var item in Model) { <tr> <td> @Html.DisplayFor(modelItem => item.UserComments) </td> @*<td> @Html.DisplayFor(modelItem => item.UserId) </td>*@ <td> @Html.ActionLink("Edit", "Edit", new { id=item.CommentId }) | @Html.ActionLink("Details", "Details", new { id=item.CommentId }) | @Html.ActionLink("Delete", "Delete", new { id=item.CommentId }) </td> </tr> } </table>功能避免重复或删除

row_number()

Answer 2

select 
     a.Serial_ID , 
     a.ISSI ,
     Date_Added 
from Asset_table  as a 
where a.Date_Added = 
     (select max(b.Date_Added) 
      from Asset_table as b  
      where b.serial = a.serial)

根据日期值删除重复项

2 个答案: