c#连接sdf文件

首先需要添加using System.Data.SqlServerCe; 引用，sdf属于SQL Server CE版本

 SqlCeConnection cc = new SqlCeConnection();
        DataTable dt = new DataTable();
        private void button1_Click(object sender, EventArgs e)
        {
            cc = new SqlCeConnection("Data Source=Database1.sdf;password=123");
            cc.Open();
            SqlCeDataAdapter ada = new SqlCeDataAdapter("select * from aa", cc);
            ada.Fill(dt);

        }

如果sdf没设置密码可以将password去掉