问题描述

我正在尝试记录唯一标识符，因此我无法承受我的 ID 的重复记录

I am trying to record unique identifiers, so I cannot afford to have a duplicate record of my ID's

当我尝试更新名为 Clients 的 SQL Server 表时，出现类似这样的错误.

I am getting an error that looks like this when I try to update my SQL Server table called Clients.

违反 PRIMARY KEY 约束PK_clients".无法插入对象db_owner.clients"中的重复键.

Violation of PRIMARY KEY constraint 'PK_clients'. Cannot insert duplicate key in object 'db_owner.clients'.

代码如下:

public void Subscribe(string clientID, Uri uri)
{
    clientsDBDataContext clientDB = new clientsDBDataContext();
    var client = new ServiceFairy.clientURI();
    client.clientID = clientID;
    client.uri = uri.ToString();
    clientDB.clientURIs.InsertOnSubmit(client);
    clientDB.SubmitChanges();
}            

我知道如何解决这个问题，所以我可以更新我的行，我想要做的就是当一行存在时只更新关联的 URI，如果它不存在则提交一个新的客户端 ID + URI，

Any Idea how I can go about fixing this, so I can update my rows, all I want to be able to do is when a row exists then only update the associated URI, and if it doesn't exist to submit a new clientID + URI,

谢谢

约翰

推荐答案

你要做的是先检查现有记录，如果不存在，再添加一条新记录.您的代码将始终尝试添加新记录.我假设您正在使用 Linq2Sql(基于 InsertOnSubmit)?

What you want to do is first check for the existing record, and if it doesn't exist, then add a new one. Your code will always attempt to add a new record. I'm assuming you're using Linq2Sql (based on the InsertOnSubmit)?

public void Subscribe(string clientID, Uri uri)
{
    using(clientsDBDataContext clientDB = new clientsDBDataContext())
    {
        var existingClient = (from c in clientDB.clientURIs
                              where c.clientID == clientID
                              select c).SingleOrDefault();

        if(existingClient == null)
        {
            // This is a new record that needs to be added
            var client = new ServiceFairy.clientURI();
            client.clientID = clientID;
            client.uri = uri.ToString();
            clientDB.clientURIs.InsertOnSubmit(client);
        }
        else
        {
            // This is an existing record that needs to be updated
            existingClient.uri = uri.ToString();
        }
        clientDB.SubmitChanges();
    }
}

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