Ошибочная инструкция sql предполагалось delete insert

I’m making an Accounting project in C# Visual Studio 2017 and I have three forms:

1. Login
2. Main
3. Product Entry

1st and 2nd form work properly, but when I clicked the button of Product Entry (3rd form),
project doesn’t go to 3rd form and it shows this error:

System.Data.OleDb.OleDbException: ‘Invalid SQL statement; expected
‘DELETE’, ‘INSERT’, ‘PROCEDURE’, ‘SELECT’, or ‘UPDATE’.’

My code is:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.OleDb;
using System.Configuration;
using MetroFramework;

namespace MAARS_Software.Project
{
    public partial class frmProductEntry : MetroFramework.Forms.MetroForm
    {
        OleDbConnection con = new 
OleDbConnection(ConfigurationManager.AppSettings["con"]);
        OleDbConnection conn = new 
OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data 
Source=D:BackupOneDriveDocumentsVisual Studio 2017My 
ProjectsBackupsMAARS SoftwareDataBase.accdb;
Jet OLEDB: Database Password = 654321");

    public frmProductEntry()
    {
        InitializeComponent();
    }

    private void frmProductEntry_Load(object sender, EventArgs e)
    {
        ViewData();
    }

    private void Save_btn_Click(object sender, EventArgs e)
    {

    }

    private void Update_btn_Click(object sender, EventArgs e)
    {

    }

    private void Delete_btn_Click(object sender, EventArgs e)
    {

    }

    private void Exit_btn_Click(object sender, EventArgs e)
    {

    }
    void ViewData()
    {
        OleDbDataAdapter da = new OleDbDataAdapter("Selct * from [Product]", 
con);
        //DataTable dt = new DataTable();
        //da.Fill(dt);
        DataSet ds = new DataSet();
        da.Fill(ds);                //Error stop here
        dataGridView1.DataSource = ds.Tables[0];
        }
    }
}

string ConStr;

string StrInsert = «Provider=Microsoft.Jet.OLEDB.4.0;Data Source=» + Application.StartupPath + «\» + «;Extended Properties=dBASE IV;User ID=Admin;Password=»;

string path = «C:\base\»;

string query = » select distinct law.pers_num_k, law.family_k, law.name_k, law.father_k, law.d_rogd_k, law.d_sm, reg.pers_num, reg.family, reg.name, reg.father, lcn.sv from lawdat_p as law, register as reg, lcn as lcn where (law.family_k is not null) and (law.name_k is not null) and (reg.num = law.num) and (reg.num = lcn.num) order by law.family_k, law.name_k, law.father_k, law.d_rogd_k, law.d_sm»;

string in_str = » insert into regdate (pers_num, family, name, father, d_rogd, d_sm, rayon, pers_num_n, family_n, father_n, name_n, sv) values (@pers_num, @family, @name, @father, @d_rogd, @d_sm, @rayon, @pers_num_n, @family_n, @father_n, @name_n, @sv)»;

DirectoryInfo dir = new DirectoryInfo(path);

DirectoryInfo[] ds = dir.GetDirectories();

foreach (DirectoryInfo d in ds)

{

  try

  {

     ConStr = «Provider=Microsoft.Jet.OLEDB.4.0;Data Source=» + path + d.Name + «\» + «;Extended Properties=dBASE IV;User ID=Admin;Password=»;

     OleDbConnection conn = new OleDbConnection(ConStr);

     OleDbCommand cmd = new OleDbCommand(query, conn);

     conn.Open();

     OleDbDataReader reader = cmd.ExecuteReader();

     while (reader.Read())

     {

         OleDbConnection conn1 = new OleDbConnection(StrInsert);

         OleDbCommand cmd1 = new OleDbCommand(in_str, conn1);

         cmd1.Parameters.Add(«@pers_num», OleDbType.Char);

         cmd1.Parameters[«@pers_num»].Value = reader[0];

         cmd1.Parameters.Add(«@family», OleDbType.Char);

         cmd1.Parameters[«@family»].Value = reader[1];

         cmd1.Parameters.Add(«@name», OleDbType.Char);

         cmd1.Parameters[«@name»].Value = reader[2];

         cmd1.Parameters.Add(«@father», OleDbType.Char);

         cmd1.Parameters[«@father»].Value = reader[3];

         cmd1.Parameters.Add(«@d_rogd», OleDbType.Date);

         cmd1.Parameters[«@d_rogd»].Value = reader[4];

         cmd1.Parameters.Add(«@d_sm», OleDbType.Date);

         cmd1.Parameters[«@d_sm»].Value = reader[5];

         cmd1.Parameters.Add(«@rayon», OleDbType.Char);

         cmd1.Parameters[«@rayon»].Value = d.Name;

         cmd1.Parameters.Add(«@pers_num_n», OleDbType.Char);

         cmd1.Parameters[«@pers_num_n»].Value = reader[6];

         cmd1.Parameters.Add(«@family_n», OleDbType.Char);

         cmd1.Parameters[«@family_n»].Value = reader[7];

         cmd1.Parameters.Add(«@name_n», OleDbType.Char);

         cmd1.Parameters[«@name_n»].Value = reader[8];

         cmd1.Parameters.Add(«@father_n», OleDbType.Char);

         cmd1.Parameters[«@father_n»].Value = reader[9];

         cmd1.Parameters.Add(«@sv», OleDbType.Char);

         cmd1.Parameters[«@sv»].Value = reader[10];

         conn1.Open();

         cmd1.ExecuteNonQuery();

         conn1.Close();    

     }

     reader.Close();

   }

   catch (Exception ex)

   {

       MessageBox.Show(ex.Message);

   }

}