索引、主键或关系中的重复值

Question

使用 JetEntityFrameworkProvider 和 MS Access/Jet 文件我正在更新实体的值，但在保存更改时收到以下错误。

OleDbException: The changes you requested to the table were not successful because they would create duplicate values in the index, primary key, or relationship. Change the data in the field or fields that contain duplicate data, remove the index, or redefine the index to permit duplicate entries and try again.

这是我的代码

var pagesList = projectDB.Pages.OrderBy(x => x.PageNumber).ToList();

for(int i = 0; i < pagesList.Count(); i++)
{
    pagesList[i].BookNumber = i+30;
}

foreach(var blah2 in pagesList.OrderBy(x => x.Id))
{
    System.Console.WriteLine($" {{ID:{blah2.Id}, BN:{blah2.BookNumber}, PN:{blah2.PageNumber}}}");

}

projectDB.SaveChanges();

这是我的代码输出，如您所见，没有重复的索引或重复的 BookNumber（已编入索引并且是唯一的）

 {ID:2, BN:58, PN:5}
 {ID:3, BN:59, PN:6}
 {ID:6, BN:62, PN:11}
 {ID:7, BN:65, PN:21}
 {ID:20, BN:64, PN:13}
 {ID:21, BN:66, PN:22}
 {ID:25, BN:67, PN:23}
 {ID:29, BN:68, PN:24}
 {ID:78, BN:35, PN:1}
 {ID:79, BN:45, PN:2}
 {ID:108, BN:34, PN:1}
 {ID:132, BN:73, PN:41}
 {ID:177, BN:33, PN:1}
 {ID:291, BN:74, PN:42}
 {ID:318, BN:32, PN:1}
 {ID:319, BN:42, PN:2}
 {ID:320, BN:48, PN:3}
 {ID:340, BN:31, PN:1}
 {ID:341, BN:41, PN:2}
 {ID:342, BN:50, PN:3}
 {ID:343, BN:53, PN:4}
 {ID:344, BN:55, PN:5}
 {ID:345, BN:60, PN:6}
 {ID:346, BN:61, PN:7}
 {ID:452, BN:71, PN:32}
 {ID:469, BN:63, PN:12}
 {ID:510, BN:72, PN:39}
 {ID:520, BN:43, PN:2}
 {ID:524, BN:75, PN:43}
 {ID:533, BN:70, PN:31}
 {ID:539, BN:69, PN:25}
 {ID:610, BN:30, PN:1}
 {ID:611, BN:36, PN:1}
 {ID:612, BN:46, PN:2}
 {ID:613, BN:37, PN:1}
 {ID:614, BN:38, PN:1}
 {ID:615, BN:44, PN:2}
 {ID:616, BN:51, PN:3}
 {ID:617, BN:52, PN:4}
 {ID:618, BN:56, PN:5}
 {ID:619, BN:40, PN:1}
 {ID:620, BN:39, PN:1}
 {ID:621, BN:47, PN:2}
 {ID:622, BN:49, PN:3}
 {ID:623, BN:54, PN:4}
 {ID:624, BN:57, PN:5}

预计到达时间：

型号

[Table("Content")]
public class Page
{
    //** Primary Key
    [Column("Counter")]
    public int Id { get; set; }

    public int ProjectCounter { get; set; }

    public short Version { get; set; }
    public short Revision { get; set; }
    public bool Locked { get; set; }

    public int DrawingType { get; set; }
    //** Forign Key?
    public int DeviceLocationCounter { get; set; }
    //** Forign Key?
    public int FolderID { get; set; }

    [Column("Page")]
    public int PageNumber { get; set; }
    //** Indexed, Unique 
    public int BookNumber { get; set; }

    public string PageIndex { get; set; }

    //** Product 
    //** DrawingObject is not here

    public bool Update { get; set; }
    public short Flag { get; set; }        
}

Answer 1

没有模型很难理解这个问题，但我认为你已经在 BookNumber 上定义了一个唯一索引。

EF 为每个更新（每个页面）运行一个 UPDATE 语句。
在某一时刻，在数据库上（不是在内存中），有 2 个实体具有相同的 BookNumber。
同样在交易中，您可能会遇到同样的问题，因此解决方案是分两个不同的步骤更新书籍

var pagesList = projectDB.Pages.OrderBy(x => x.PageNumber).ToList();

for (int i = 0; i < pagesList.Count; i++)
    pagesList[i].BookNumber = null;

projectDB.SaveChanges();

for (int i = 0; i < pagesList.Count; i++)
    pagesList[i].BookNumber = i + 30;

foreach (var blah2 in pagesList.OrderBy(x => x.Id))
    Console.WriteLine("{{ID:{0}, BN:{1}, PN:{2}}}", blah2.Id, blah2.BookNumber, blah2.PageNumber);

projectDB.SaveChanges();

索引、主键或关系中的重复值

duplicate values in the index, primary key, or relationship

jet-ef-provider