命名空间“dll”中不存在类型或命名空间名称“yonghu”(是缺少程序集引用吗?)

Question

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.OleDb;
namespace dll
{
    public class lianjie
    {        OleDbConnection conn = new OleDbConnection();
        public object yong(string sql)
        {
            try
            {
                conn.Open();
                conn.ConnectionString = "provider=sqloledb.1;data source=.;initial catalog=jpl;user id=sa;pwd=;";
                OleDbCommand cmd = new OleDbCommand(sql, conn);
                object o = cmd.ExecuteScalar();
                return o;
            }
            catch { }
            finally
            {
                if (conn != null)
                {
                    conn.Close();
                    conn.Dispose();
                }
            }
            return null;
        }    }
}

Answer 1

namespace dll 
建議把命名空間的名稱改掉