How to import external sqlite database for the login form?

i need to know that whats wrong with my code? I had used the code from here itself of sqlite database file tobe imported exrernally & used it as database for login of my application.

Login_Activity:

public class Login_Activity extends Activity{

Intent i=null;
ImageView im=null;
EditText ed1,ed4,ed5;
boolean flag=false;
SQLiteDatabase db=null;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login);


    ed1=(EditText)findViewById(R.id.loginid);
    ed4=(EditText)findViewById(R.id.password2);

    db=openOrCreateDatabase("mydatabase", MODE_PRIVATE, null);
}
public void action(View v)
{
switch(v.getId())
{
 case R.id.start:
    String loginid=tv1.getText().toString();
    String password=tv4.getText().toString();

    if(loginid==null||loginid==""||loginid.length()<4)
    {
        show("Please Enter Correct id.");
    }
    else if(password==null||password==""||password.length()<6)
    {
        show("Please Enter Correct Password.");
    }
    else
    {       
        Cursor c=db.rawQuery("select * from trial where loginid='"+loginid+"' and password='"+password+"'",null);   
        c.moveToFirst();
        if(c.getCount()>0 && loginid.startsWith("M"))
        {                           
        i=new Intent(this,Welcome_Manager.class);
        startActivityForResult(i,500);
        overridePendingTransition(R.anim.slide_in_right, R.anim.slide_out_left); 
        db.close();
        finish();
        }