接收存储过程返回字符串
存储过程代码

SQL code

ALTER  PROCEDURE p_UpdateTree(@MenuName nvarchar(50),@MenuFather nvarchar(50),@MenuGroup nvarchar(50),@New_MenuName nvarchar(50),@NewMenuAddress char(60),@MenuShow bit,@RValue nvarchar(10) output)ASSET NOCOUNT ONUpdate ControlTree Set MenuName=@New_MenuName,MenuAddress=@NewMenuAddress,MenuShow=@MenuShowWhere  MenuName=@MenuName AND MenuFather=@MenuFather AND MenuGroup= @MenuGroupIF @@ROWCOUNT>0     begin        set @RValue='OK'    end    ELSE    begin        set @RValue='Failed'    end    select @RValueGO

程序接收代码

VB.NET code

Public Function UpdateTree(ByVal MenuName As String, ByVal MenuFather As String, ByVal MenuGroup As String, ByVal New_MenuName As String, ByVal NewMenuAddress As String, ByVal MenuShow As Integer) As Boolean        Dim SqlCon As New SqlConnection        SqlCon = Consql()        Dim SqlComm As New SqlCommand("p_UpdateTree", SqlCon)        If SqlCon.State Then            Try                With SqlComm                    .CommandType = CommandType.StoredProcedure                    .Parameters.Add(New SqlParameter("@MenuName", MenuName))                    .Parameters.Add(New SqlParameter("@MenuFather", MenuFather))                    .Parameters.Add(New SqlParameter("@MenuGroup", MenuGroup))                    .Parameters.Add(New SqlParameter("@New_MenuName", New_MenuName))                    .Parameters.Add(New SqlParameter("@NewMenuAddress", NewMenuAddress & " "))                    .Parameters.Add(New SqlParameter("@MenuShow", MenuShow))                    .Parameters.Add(New SqlParameter("@RValue", "5"))                    .Parameters("@RValue").Direction = ParameterDirection.Output                    .ExecuteNonQuery()                End With                Dim i As String                i = SqlComm.Parameters("@RValue").Value.ToString.Trim()'这里是用来调试模式看返回值，总是返回空                If String.Equals(SqlComm.Parameters("@RValue").Value.ToString.Trim(), "OK") Then                    Return True                Else                    Return False                End If            Catch ex As Exception            Finally                SqlComm.Dispose()                If SqlCon.State Then SqlCon.Close()                SqlCon.Dispose()            End Try        Else            HttpContext.Current.Response.Write("打开数据库失败。请与管理员联系！")            HttpContext.Current.Response.End()        End If

存储过程我用查询分析器调试 完全正常 可以输出 OK 和Failed
但是用程序来接收返回值的时候，老是返回的空值。请大家帮忙看看是哪的问题
谢谢！！

[解决办法]
.Parameters.Add(New SqlParameter("@RValue", "5")) //老是感觉好象不对劲

你改为看看
.Parameters.Add(New SqlParameter("@RValue", SqlDbType.NVarChar,10))