Question

我正在使用实体框架将用户添加到数据库。 当我将第一个用户添加到数据库时，它可以工作。尝试将另一个用户添加到数据库时，出现错误：System.Data.SqlClient.SqlException：违反UNIQUE KEY约束

我不太确定我在这里做什么。我什至已经制定了IF条件来检查天气，钥匙是唯一的，但实际错误消息说我正在插入重复的钥匙。

这是我当前的代码：

//Create new GUID
string newGuid = Guid.NewGuid().ToString();

//Checking if Primary Key already exists in table
if (!context.Users_tbl.Any(u => u.UserID == newGuid))
{

//Installise New User Class
var user = new Users_tbl()
{
UserID = newGuid,
Email = email,
Password = AESCrypt.Encrypt(password),
};

//Add User to ADO and Commit Changes
context.Users_tbl.Add(user);
context.SaveChanges();

//Find UserID via Email
var userID = context.Users_tbl.Where(p => p.Email == email).Select(p => p.UserID).FirstOrDefault();

//Installise New UserInfo Class
var usersInfo = new UsersInfo_tbl()
{
FKUserID = userID,
FirstName = firstName,
LastName = lastName
};

//Add User to ADO and Commit Changes
context.UsersInfo_tbl.Add(usersInfo);
context.SaveChanges();

//Send Activation Link via Email
SendActivationEmail(userID);

//Set Session ID
Session["UserID"] = userID;
Response.Redirect("/Dashboard/DashBoard.aspx", false);
}

下面是我收到的确切错误消息。

System.Data.Entity.Infrastructure.DbUpdateException: An error occurred while updating the entries. See the inner exception for details. ---> System.Data.Entity.Core.UpdateException: An error occurred while updating the entries. See the inner exception for details. ---> System.Data.SqlClient.SqlException: Violation of UNIQUE KEY constraint 'UQ__Users_tb__2B5B96C51C3AA70E'. Cannot insert duplicate key in object 'dbo.Users_tbl'. The duplicate key value is (<NULL>).
The statement has been terminated.
   at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
   at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
   at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString, Boolean isInternal, Boolean forDescribeParameterEncryption, Boolean shouldCacheForAlwaysEncrypted)
   at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, Boolean inRetry, SqlDataReader ds, Boolean describeParameterEncryptionRequest)
   at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean& usedCache, Boolean asyncWrite, Boolean inRetry)
   at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean& usedCache, Boolean asyncWrite, Boolean inRetry)
   at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
   at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.<NonQuery>b__0(DbCommand t, DbCommandInterceptionContext`1 c)
   at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch[TTarget,TInterceptionContext,TResult](TTarget target, Func`3 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 executed)
   at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.NonQuery(DbCommand command, DbCommandInterceptionContext interceptionContext)
   at System.Data.Entity.Internal.InterceptableDbCommand.ExecuteNonQuery()
   at System.Data.Entity.Core.Mapping.Update.Internal.DynamicUpdateCommand.Execute(Dictionary`2 identifierValues, List`1 generatedValues)
   at System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.Update()
   --- End of inner exception stack trace ---
   at System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator.Update()
   at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.<Update>b__2(UpdateTranslator ut)
   at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.Update[T](T noChangesResult, Func`2 updateFunction)
   at System.Data.Entity.Core.EntityClient.Internal.EntityAdapter.Update()
   at System.Data.Entity.Core.Objects.ObjectContext.<SaveChangesToStore>b__35()
   at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
   at System.Data.Entity.Core.Objects.ObjectContext.SaveChangesToStore(SaveOptions options, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction)
   at System.Data.Entity.Core.Objects.ObjectContext.<>c__DisplayClass2a.<SaveChangesInternal>b__27()
   at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
   at System.Data.Entity.Core.Objects.ObjectContext.SaveChangesInternal(SaveOptions options, Boolean executeInExistingTransaction)
   at System.Data.Entity.Core.Objects.ObjectContext.SaveChanges(SaveOptions options)
   at System.Data.Entity.Internal.InternalContext.SaveChanges()
   --- End of inner exception stack trace ---
   at System.Data.Entity.Internal.InternalContext.SaveChanges()
   at System.Data.Entity.Internal.LazyInternalContext.SaveChanges()
   at System.Data.Entity.DbContext.SaveChanges()
   at ReapStreamV2.Auth.Signup.SignUp.Submit_Click(Object sender, EventArgs e) in C:\Users\Milan\Documents\ReapStream DEV\ReapStream\ReapStreamV2\Auth\Signup\SignUp.aspx.cs:line 123

我的主键是唯一的；

```
CREATE TABLE [dbo].[Users_tbl] (
    [UserID]            NVARCHAR (128) NOT NULL,
    [Email]             VARCHAR (255)  NOT NULL,
    [Password]          VARCHAR (255)  NOT NULL,
    [IsTwoFAEnabled]    BIT            NOT NULL,
    [TwoFACode]         NVARCHAR (128) NULL,
    [hasActivated]      BIT            NOT NULL,
    [AccessFailedCount] INT            NOT NULL,
    CONSTRAINT [PK__Users_tb__1788CCAC29DEB237] PRIMARY KEY CLUSTERED ([UserID] ASC),
    CONSTRAINT [UQ__Users_tb__2B5B96C51C3AA70E] UNIQUE NONCLUSTERED ([TwoFACode] ASC)
);

```

Answer 1

错误消息指出“违反UNIQUE KEY约束'UQ__Users_tb__2B5B96C51C3AA70E'。无法在对象'dbo.Users_tbl'中插入重复键。重复键值为（）。“

在消息的下部，我看到UQ__Users_tb__2B5B96C51C3AA70E与TwoFACode字段相关。

在将用户添加到表的代码中，您尚未填充此字段-因此违反了带有两个空条目的唯一约束。

“ [TwoFACode] NVARCHAR（128）NULL ”-该字段允许为空-但由于约束，只能有一个空字段。

Answer 2

要进一步了解PaulF的评论，

var usersInfo = new UsersInfo_tbl()
{
    FKUserID = userID,
    FirstName = firstName,
    LastName = lastName
};

这将设置FKUserID，但是您尚未为此表设置ID，因此您尝试插入一个null值，这就是错误告诉您的内容：The duplicate key value is (<NULL>).这里要注意的关键是它是UsersInfo_tbl表，而不是Users_tbl表。由于您尚未包括UsersInfo_tbl表的架构，因此我们不知道该表的主要含义是什么，或者它是否允许null。如果确实如此（看起来确实如此），则不应该如此。尝试查看两个表的数据以确切了解发生了什么。

这还表示您的表中已经有一个null值，很可能需要使用实际值对其进行更新。

作为一个旁注，我发现在表名上添加“ tbl”相当糟糕。除了外观和感觉很差之外，它还会在以后导致问题。其他人也认为这是不好的做法。

https://dba.stackexchange.com/questions/154251/is-adding-the-tbl-prefix-to-table-names-really-a-problem

Answer 3

恕我直言，您应该确保“电子邮件”列是唯一的，因为现在您可以获得一个以上的用户（如果数据库中有更多具有相同电子邮件的用户，并且您要求第一个用户，则用户ID的更改将是随机的）：

//Find UserID via Email
var userID = context.Users_tbl.Where(p => p.Email == email).Select(p => p.UserID).FirstOrDefault();

确保您使用的是EntityFramework库中的Find（）方法，它将通过ID键获取用户（它将首先从上下文中获取数据，而不是访问数据库），而不是使用Where（）linq方法来查询数据库。

如果您的代码属于一种方法的范围，则不必询问上下文或数据库是否存在用户，而是使用newGuid值从“ UsersInfo_tbl”设置“ FKUserID”属性。

Answer 4

尝试在代码中设置guid会填充对象的其余部分（不包括guid），这是一种不好的做法。

var user = new Users_tbl()
{
//UserID = newGuid, You dont need this.
Email = email,
Password = AESCrypt.Encrypt(password),
};

YourRepository.SaveChanges();
var userId = user.UserId; (this should retrieve the guid back).

此外，您在表中的UserId不应为nvarchar，而应为UniqueIdentifer

在SSMS中打开表格，您可以为Guid设置默认值

或运行命令为您更改它。

ALTER TABLE dbo.Users_tbl
   ALTER [UserId] UNIQUEIDENTIFIER DEFAULT NEWID() PRIMARY KEY;

如何修复“违反UNIQUE KEY约束”

4 个答案: