Android sqlite local database

The same is true for Android databases used for any development. Android generally uses two databases: local database and remote database. The local database is sqlite, I usually use mysql. This time, I first learned about the local database sqlite. The general database type is varchar (20). If you input a data greater than 20 bits, an error is returned, you can't insert it, but it's different in sqlite. It's one of the characteristics of sqlite. Let's take a look at the crud of sqlite:

MainActivity

package com.example.sqlite;import android.os.Bundle;import android.app.Activity;import android.view.Menu;import android.widget.TextView;public class MainActivity extends Activity {    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        TextView t;                DBOpenHelter dbopenhelper=new DBOpenHelter(this);    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        getMenuInflater().inflate(R.menu.activity_main, menu);        return true;    }}

PersonService

Package com. example. sqlite; import com. example. bean. person; import android. content. context; import android. database. cursor; import android. database. sqlite. SQLiteDatabase; public class PersonService {private DBOpenHelter dbOpenHelper; public PersonService (Context context) {this. dbOpenHelper = new DBOpenHelter (context);} public void save (Person person) {SQLiteDatabase db = dbOpenHelper. getWritableDatabase (); Strin GBuilder SQL = new StringBuilder (128); // This SQL is useless. append ("insert"); // This does not use db.exe cSQL ("insert into person (name, phone) values (?,?) ", New Object [] {person. getName (), person. getPhone ()}); db. close () ;}public Person find (Integer id) {Person person = new Person (); SQLiteDatabase db = dbOpenHelper. getReadableDatabase (); Cursor cursor = db. rawQuery ("select * from testpersion wehre name =? ", New String [] {id. toString ()}); while (cursor. moveToNext () {int personid = cursor. getInt (cursor. getColumnIndex ("id");} return person ;}}

DBOpenHelter

Package com. example. sqlite;

Import android. content. Context;
Import android. database. sqlite. SQLiteDatabase;
Import android. database. sqlite. SQLiteDatabase. CursorFactory;
Import android. database. sqlite. SQLiteOpenHelper;

Public class DBOpenHelter extends SQLiteOpenHelper {

Public DBOpenHelter (Context context ){
Super (context, "itcast. db", null, 1 );
}

@ Override
Public void onCreate (SQLiteDatabase db ){
Db.exe cSQL ("create table testpersion (persionid integer primary key autoincrement, name varchar (20 ))");
}

@ Override
Public void onUpgrade (SQLiteDatabase db, int oldVersion, int newVersion ){
// TODO Auto-generated method stub
Db.exe cSQL ("alter table testpersion ADD phone VARCHAR (12) NULL ");
}

}