C# ODP.NET 调用Oracle函数返回值时报错的一个解决方案

CREATE OR REPLACE FUNCTION F_Update_Grade(v_UserID in Number) return nvarchar2 is V_Grade nVARCHAR2(20);begin V_Grade := '1205'; update TESTDB3 set Grade = V_Grade where PKID = v_UserID; commit; return (V_Grade);end F_Update_Grade;

declare V_Result nvarchar2(1000) := ''; V_UserID number(10) := 1;begin V_Result := f_update_grade(V_UserID);  dbms_output.put_line('Value:' || V_Result);end;/*Value:1205*/

using Oracle.ManagedDataAccess.Client;using System;using System.Data;using System.Data.SqlClient;namespace TestOracle_ManagedDataAccess{  class Program  {    static void Main(string[] args)    {      TestFUNCTION3();      Console.ReadLine();    }    static void TestFUNCTION3()    {      string strConn = "Data Source=127.0.0.1/BCS;User ID=user2019;Password=password9102";      //OracleConnection objConn = new OracleConnection(strConn);      string strFun = "F_Update_Grade";      //string strFun = "F_Get_Grade";      using (OracleConnection objConn = new OracleConnection(strConn))      {        using (OracleCommand cmd = new OracleCommand(strFun, objConn))        {          try          {            // 获取选中行            //int strRowIdex = 1;            // 创建参数对象            OracleParameter p1 = new OracleParameter("v_UserID", OracleDbType.Int32, ParameterDirection.Input);            OracleParameter p2 = new OracleParameter("V_Grade", OracleDbType.NVarchar2, 20);            p1.Value = 1;//取PKID为1的记录            p2.Direction = ParameterDirection.ReturnValue;            // 更新数据库表            cmd.CommandType = CommandType.StoredProcedure;            objConn.Open();            /***************************************************************             * 注意，输出参数一定要第一个加，函数的返回值也是赋给第一个参数*;              * *************************************************************/            cmd.Parameters.Add(p1);            cmd.Parameters.Add(p2);            cmd.ExecuteNonQuery();            //返回结果值            Console.WriteLine("V_Grade is :" + p2.Value.ToString());            Console.WriteLine("OK");          }          catch (SqlException ex)          {            objConn.Close();            Console.WriteLine("ERROR in :" + ex.Message);          }          finally          {            cmd.Dispose();            objConn.Close();          }        }      }    }

update testdb3 set grade=1 where PKID=1;