Oracle.ManagedDataAccess.Client.OracleException:“ORA-00936: 缺失表达式”

static void main(string[] args)
        {

            string sql = "insert into studentc(stuid, stuname, stupass) values(@stuid,@stuname,@stupass)";
            oracleparameter[] parameters =
            {
                new oracleparameter("@stuid",oracledbtype.int32,2),
                new oracleparameter("@stuname",oracledbtype.varchar2,20),
                new oracleparameter("@stupass",oracledbtype.varchar2,20)
            };
            parameters[0].value = 3;
            parameters[1].value = "疯了";
            parameters[2].value = "studen";
            db_helper_dg.executenonquery(sql, commandtype.text,parameters);

        }

这是我最开始写的代码，讲@符号换成：，因为@符号是sqlserver中的写法。