对 Oracle 的 EF 查询抛出“ORA-12704：字符集不匹配”

Posted 2023-03-31

【中文标题】对 Oracle 的 EF 查询抛出“ORA-12704：字符集不匹配”

【英文标题】：EF query to Oracle throwing "ORA-12704: character set mismatch"

【发布时间】：2017-10-02 04:37:45

【问题描述】：

我正在尝试合并来自 Oracle 的 EF 中的几列，然后在这些列上执行 .Contains()，如下所示：

public IEnumerable<User> SearchUsers(string search)

    search = search.ToLower();

    return _securityUow.Users
            .Where(u => (u.FirstName.ToLower() + " " + u.LastName.ToLower() + " (" + u.NetId.ToLower() + ")").Contains(search))
            .OrderBy(u => u.LastName)
            .ThenBy(u => u.FirstName)
            .AsEnumerable();

但是，我遇到了这个异常：

  "Message": "An error has occurred.",
  "ExceptionMessage": "An error occurred while executing the command definition. See the inner exception for details.",
  "ExceptionType": "System.Data.Entity.Core.EntityCommandExecutionException",
  "StackTrace": "   at SoftwareRegistration.WebUI.Controllers.Api.V1.UserContactController.Lookup(String search) in C:\LocalRepository\OnlineSupport\SoftwareRegistration\trunk\release\SoftwareRegistration\SoftwareRegistration.WebUI\Controllers\Api\V1\UserContactController.cs:line 40\r\n   at lambda_method(Closure , Object , Object[] )\r\n   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass10.<GetExecutor>b__9(Object instance, Object[] methodParameters)\r\n   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.Execute(Object instance, Object[] arguments)\r\n   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ExecuteAsync(HttpControllerContext controllerContext, IDictionary`2 arguments, CancellationToken cancellationToken)\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()\r\n   at System.Web.Http.Controllers.ApiControllerActionInvoker.<InvokeActionAsyncCore>d__0.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()\r\n   at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d__2.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()",
  "InnerException": 
    "Message": "An error has occurred.",
    "ExceptionMessage": "ORA-12704: character set mismatch",
    "ExceptionType": "Oracle.ManagedDataAccess.Client.OracleException",
    "StackTrace": "   at OracleInternal.ServiceObjects.OracleCommandImpl.VerifyExecution(OracleConnectionImpl connectionImpl, Int32& cursorId, Boolean bThrowArrayBindRelatedErrors, OracleException& exceptionForArrayBindDML, Boolean& hasMoreRowsInDB, Boolean bFirstIterationDone)\r\n   at OracleInternal.ServiceObjects.OracleCommandImpl.ExecuteReader(String commandText, OracleParameterCollection paramColl, CommandType commandType, OracleConnectionImpl connectionImpl, OracleDataReaderImpl& rdrImpl, Int32 longFetchSize, Int64 clientInitialLOBFS, OracleDependencyImpl orclDependencyImpl, Int64[] scnForExecution, Int64[]& scnFromExecution, OracleParameterCollection& bindByPositionParamColl, Boolean& bBindParamPresent, Int64& internalInitialLOBFS, OracleException& exceptionForArrayBindDML, Boolean isDescribeOnly, Boolean isFromEF)\r\n   at Oracle.ManagedDataAccess.Client.OracleCommand.ExecuteReader(Boolean requery, Boolean fillRequest, CommandBehavior behavior)\r\n   at Oracle.ManagedDataAccess.Client.OracleCommand.ExecuteDbDataReader(CommandBehavior behavior)\r\n   at System.Data.Common.DbCommand.ExecuteReader(CommandBehavior behavior)\r\n   at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.<Reader>b__c(DbCommand t, DbCommandInterceptionContext`1 c)\r\n   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)\r\n   at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.Reader(DbCommand command, DbCommandInterceptionContext interceptionContext)\r\n   at System.Data.Entity.Internal.InterceptableDbCommand.ExecuteDbDataReader(CommandBehavior behavior)\r\n   at System.Data.Common.DbCommand.ExecuteReader(CommandBehavior behavior)\r\n   at System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition.ExecuteStoreCommands(EntityCommand entityCommand, CommandBehavior behavior)"
  

我查询的列都是 Oracle 中的 VARCHAR2(128) 类型。

我也在另一个项目中使用了完全相同的代码，它可以工作。唯一的区别是，对于有效的项目，我使用Oracle.DataAccess，而对于无效的项目，我使用Oracle.ManagedDataAccess（我无法在这个项目中使用Oracle.DataAccess）。所以我相信托管驱动程序中存在错误/问题。

我愿意接受解决方案或变通办法。

【问题讨论】：

您的数据库使用什么字符集？运行SELECT * FROM NLS_DATABASE_PARAMETERS WHERE PARAMETER = 'NLS_CHARACTERSET' 来确定这一点。

我跑了，上面写着WE8MSWIN1252

嗯，这与我的预期相反。 WE8MSWIN1252 是一个单字节字符集，但 IIRC .net 在内部使用 Unicode，所以我希望数据库或驱动程序应该能够从单字节数据库字符集到/从单字节数据库字符集转换为 Unicode。我查看了OracleGlobalization class docs，看起来在托管驱动程序下没有任何允许设置字符集的方法可用。祝你好运。

事实上，ODP.NET 托管驱动程序对 NLS_LANG 不敏感。它仅对 .NET 语言环境敏感，请参阅 Globalization Support。当您尝试使用 ToLower(CultureInfo) 时，它可能会有所帮助。

【参考方案1】：

我最终让这个 (ODP.Net Managed Driver - ORA-12704: character set mismatch in generated code) 的作者更新了这个问题，他发布了一个使用拦截器的解决方法，我会在这里更详细一点......

首先，我装饰了我的 DBContext 以加载配置。你可以跳过这个，如果你有一个，只需添加到你的配置中：

[DbConfigurationType(typeof(MyDbConfiguration))]
public partial class MyContext : DbContext

创建配置类：

public class MyDbConfiguration : DbConfiguration

    public MyDbConfiguration()
    
        this.AddInterceptor(new NVarcharInterceptor()); //add this line to existing config.
    

接下来，创建拦截器：

public class NVarcharInterceptor : IDbCommandInterceptor

    public void NonQueryExecuted(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    
        if (command != null && !string.IsNullOrWhiteSpace(command.CommandText))
            command.CommandText = command.CommandText.Replace("N''", "''");
    

    public void NonQueryExecuting(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    
        if (command != null && !string.IsNullOrWhiteSpace(command.CommandText))
            command.CommandText = command.CommandText.Replace("N''", "''");
    

    public void ReaderExecuted(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    
        if (command != null && !string.IsNullOrWhiteSpace(command.CommandText))
            command.CommandText = command.CommandText.Replace("N''", "''");
    

    public void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    
        if (command != null && !string.IsNullOrWhiteSpace(command.CommandText))
            command.CommandText = command.CommandText.Replace("N''", "''");
    

    public void ScalarExecuted(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    
        if (command != null && !string.IsNullOrWhiteSpace(command.CommandText))
            command.CommandText = command.CommandText.Replace("N''", "''");
    

    public void ScalarExecuting(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    
        if (command != null && !string.IsNullOrWhiteSpace(command.CommandText))
            command.CommandText = command.CommandText.Replace("N''", "''");
    

【讨论】：

请注意：如果您的字符串物理上包含字符串 N''，那么您会大吃一惊。只是我的2c。最重要的是，该方法可能会更好，它转换为 N' -> ' （而不是 N'' -> ''）

【参考方案2】：

在这些情况下，最好手动连接这些查询，具体取决于列是否为 unicode，其中一些方式

return _securityUow.Users
    .Where(u => (u.FirstName.ToLower() + DbFunctions.AsNonUnicode(" ") + u.LastName.ToLower() + DbFunctions.AsNonUnicode(" (") + u.NetId.ToLower() + DbFunctions.AsNonUnicode(")")).Contains(search))
    ...

return _securityUow.Users
    .Where(u => (u.FirstName.ToLower() + DbFunctions.AsUnicode(" ") + u.LastName.ToLower() + DbFunctions.AsUnicode(" (") + u.NetId.ToLower() + DbFunctions.AsUnicode(")")).Contains(search))
    ...

取决于列的类型是 NVarchar 还是 Varchar（默认情况下 EF 使用 nvarchar，除非属性中设置了 .isUnicode）