Объединение нескольких таблиц в одну

string query = "SELECT * INTO [R1] FROM [U1]";
//выполнение запроса
string query = "SELECT * INTO [R1] FROM [U2]";
//выполнение запроса
//...

string crd = "Connect";
           OleDbConnection con = new OleDbConnection();
           con.ConnectionString = crd;
           con.Open();
 
          string query = "SELECT * INTO [R1] FROM [U1] ";
          string query_1 = "SELECT * INTO [R1] FROM [U3] ";
 
          OleDbDataAdapter adapter = new OleDbDataAdapter(query, con);
 
           con.Close();
 
 
           adapter.SelectCommand.ExecuteNonQuery();

string crd = "Connect";
           OleDbConnection con = new OleDbConnection();
           con.ConnectionString = crd;
           con.Open();
 
          string query = "SELECT * INTO [R1] FROM [U1] ";
          string query_1 = "SELECT * INTO [R1] FROM [U3] ";
 
          OleDbDataAdapter adapter = new OleDbDataAdapter(query, con);
          OleDbDataAdapter adapter_1 = new OleDbDataAdapter(query_1, con);
 
           con.Close();
 
 
           adapter.SelectCommand.ExecuteNonQuery(); 
           //adapter_1.SelectCommand.ExecuteNonQuery();

using (OleDbConnection con = new OleDbConnection(строка_подключения))
{
    con.Open();
    OleDbCommand com = new OleDbCommand();
    com.Connection = con;
    com.CommandText = "insert into R1 select * from U1";
    com.ExecuteNonQuery();
    com.CommandText = "insert into R1 select * from U2";
    com.ExecuteNonQuery();
    con.Close();
}

using (OleDbConnection con = new OleDbConnection("Provider = Microsoft.Jet.Oledb.4.0; ...))
           {
               con.Open();
               OleDbCommand com = new OleDbCommand();
               com.Connection = con;
               com.CommandText = "SELECT * INTO [R1] FROM [U1] ";
               com.ExecuteNonQuery();
               //com.CommandText = "SELECT * INTO [R1] FROM [U3] ";
               //com.ExecuteNonQuery();
               con.Close();
           }