MySql + entity framework =每个派生表都必须有自己的别名

Question

我必须从我的C#程序访问另一个开发人员的一些MySql视图.

所以在经过一些搜索之后我决定实体框架,并使用这个问题中提到的驱动程序:使用MySQL和Entity Framework(MySQL .NET Connector).

现在,我正在尝试获取一个视图的第一个元素:

myEntities.events.First();

在那里,我得到一个例外:

System.Data.EntityCommandExecutionException was unhandled
  Message=An error occurred while executing the command definition. See the inner exception for details.
  Source=System.Data.Entity
  StackTrace:
       at System.Data.EntityClient.EntityCommandDefinition.ExecuteStoreCommands(EntityCommand entityCommand, CommandBehavior behavior)
       at System.Data.Objects.Internal.ObjectQueryExecutionPlan.Execute[TResultType](ObjectContext context, ObjectParameterCollection parameterValues)
       at System.Data.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
       at System.Data.Objects.ObjectQuery`1.System.Collections.Generic.IEnumerable<T>.GetEnumerator()
       at System.Linq.Enumerable.First[TSource](IEnumerable`1 source)
       at System.Data.Objects.ELinq.ObjectQueryProvider.<GetElementFunction>b__0[TResult](IEnumerable`1 sequence)
       at System.Data.Objects.ELinq.ObjectQueryProvider.ExecuteSingle[TResult](IEnumerable`1 query, Expression queryRoot)
       at System.Data.Objects.ELinq.ObjectQueryProvider.System.Linq.IQueryProvider.Execute[S](Expression expression)
       at System.Linq.Queryable.First[TSource](IQueryable`1 source)
       at J4N.GroopleReports.ReportManager.DataImporter.GenerateEvent(GroopleEntities groopleEntities) in C:\Users\J4N\Dropbox\WorkSpaces\DotNET\GroopleReports\ReportManager\DataImporter.cs:line 35
       at J4N.GroopleReports.ReportManager.DataImporter.Import() in C:\Users\J4N\Dropbox\WorkSpaces\DotNET\GroopleReports\ReportManager\DataImporter.cs:line 17
       at ImportTest.Program.Main(String[] args) in C:\Users\J4N\Dropbox\WorkSpaces\DotNET\GroopleReports\ImportTest\Program.cs:line 15
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: MySql.Data.MySqlClient.MySqlException
       Message=Every derived table must have its own alias
       Source=MySql.Data
       ErrorCode=-2147467259
       Number=1248
       StackTrace:
            at MySql.Data.MySqlClient.MySqlStream.ReadPacket()
            at MySql.Data.MySqlClient.NativeDriver.GetResult(Int32& affectedRow, Int32& insertedId)
            at MySql.Data.MySqlClient.Driver.GetResult(Int32 statementId, Int32& affectedRows, Int32& insertedId)
            at MySql.Data.MySqlClient.Driver.NextResult(Int32 statementId, Boolean force)
            at MySql.Data.MySqlClient.MySqlDataReader.NextResult()
            at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)
            at MySql.Data.Entity.EFMySqlCommand.ExecuteDbDataReader(CommandBehavior behavior)
            at System.Data.Common.DbCommand.ExecuteReader(CommandBehavior behavior)
            at System.Data.EntityClient.EntityCommandDefinition.ExecuteStoreCommands(EntityCommand entityCommand, CommandBehavior behavior)
       InnerException: 

我搜索了什么是这个错误"每个派生表必须有自己的别名"以及如何解决它,我在网上发现了一些关于SQL请求有什么问题的回复,但我无法影响实体框架如何构建它们.

Answer 1

除了接受的答案之外,还应注意,Every derived table must have its own alias如果您尝试在没有主键的表上保存数据库中的更改,则会抛出相同的异常().

这是一个已知的错误,多年后仍然没有修复(出现在MySQL 5.5.22 + .Net/Connector 6.5.4于04/04/12).

我知道拥有一个没有主键的表并不是一个好主意,但是由于DDL生成器中还有另一个错误,因此创建了没有主键的关联实体键具有属性StoreGeneratedPattern设置的一些表None...