因存储过程参数类型不匹配而造成OledbCommand的不可用XML:namespace prefix = o ns = "urn:schemas-microsoft-com:Office:office" />

Key words:

  Stored Procedure/OleDbCommand/ado.NET/Parameter/Type/存储过程/参数/类型

  在讨论OleDbCommand出错之前，还是想了解以下OleDbCommand一些运行机制。在数据库里面有如下存储过程：

ALTER PROCEDURE dbo.Test

@Name  nvarchar(50),

@Age  smallint

AS

select @Name, @Age

使用以下代码调用，并用Watch监视OleDbCommand实例的内存状况：

using System;

using System.Data;

using System.Data.OleDb;

namespace testCommand

{

  class Class1

  {

  [STAThread]

  static void Main(string[] args)

  {

  OleDbConnection conn=new OleDbConnection("xxx");

  conn.Open();

  OleDbCommand comm=new OleDbCommand("Test",conn);

  comm.CommandType=CommandType.StoredProcedure;

  OleDbCommandBuilder.DeriveParameters(comm);

  try

  {

  comm.Parameters["Name"].Value="my name";

  comm.Parameters["Age"].Value=(object)11;

    comm.ExecuteNonQuery();  //断点一，此处内存状况见表一

  }

  catch(Exception err)

  {

  Console.WriteLine(

  err.TargetSite+" -- "+err.StackTrace+" -- "+

  err.source+" -- "+err.Message+" -- "+

  err.GetType().ToString());

  }

  try

  {

  comm.Parameters["Name"].Value="my name";

  comm.Parameters["Age"].Value=(object)11;

  comm.ExecuteNonQuery();  //断点二，此处内存状况见表二

  }

  catch(Exception err)

  {

  Console.WriteLine(

  err.TargetSite+" -- "+err.StackTrace+" -- "+

  err.Source+" -- "+err.Message+" -- "+

  err.GetType().ToString());

  }

  conn.Close();

  }

  }

}

表格一，断点一处的内存状况

-

comm

{System.Data.OleDb.OleDbCommand}

System.Data.OleDb.OleDbCommand

transaction

null

System.Data.OleDb.OleDbTransaction

cmdText

Test

string

cmdType

StoredProcedure

System.Data.CommandType

updatedRowSource

Both

System.Data.UpdateRowSource

commandTimeout

30

int

icommandText

null

System.Data.Common.UnsafeNativeMethods.ICommandText

handle_Accessor

0

int

commandBehavior

Default

System.Data.CommandBehavior

dbBindings

null

System.Data.OleDb.DBBindings

canceling

FALSE

bool

isPrepared

FALSE

bool

executeQuery

FALSE

bool

computedParameters

FALSE

bool

designTimeVisible

FALSE

bool

cmdState

0

int

recordsAffected

0

int

CommandText

Test

string

CommandTimeout

30

int

CommandType

StoredProcedure

System.Data.CommandType

DesignTimeVisible

TRUE

bool

IsClosed

TRUE

bool

Transaction

null

System.Data.OleDb.OleDbTransaction

UpdatedRowSource

Both

System.Data.UpdateRowSource