使用方法如下

public void opensql()
        {
            //SqlCommand cm = new System.Data.SqlClient.SqlCommand();
            //SqlConnection cn = new SqlConnection();
            SqlCeCommand cm = new SqlCeCommand();
            SqlCeConnection cn = new SqlCeConnection();
            //cn.ConnectionString = "Data Source=symbol.sdf";
            //cn.ConnectionString = "server=JC91109;uid=sa;pwd=sa;database=symbol";
            string appPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().GetName().CodeBase.ToString());
            string dbcStr = @"Data Source =" + appPath.Replace(@"\\", @"\") + @"\symbol.sdf";
            cn.ConnectionString = ""+dbcStr+"";
            cn.Open();
            cm.Connection = cn;
        }

private void button1_Click(object sender, EventArgs e)
        {
            opensql();
            cm.CommandText = "insert into scan(barcode) values('123')";
            cm.ExecuteNonQuery();
            SqlDataReader rs = cm.ExecuteReader();

        }

在PDA中运行报错，在cm.CommandText = "insert into scan(barcode) values('123')";处显示没有NEW对象的实例。

在PDA的程序当前目录下有SYMBOL.SDF文件并有表SCAN.