android 数据库 总结

package com.example.wxj2048;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class Dbdao extends SQLiteOpenHelper{

	private static final String DBNAME = "mldn.db";
	private static final int DBVERSION = 1;
	private static final String TABNAME = "game2048";
	
	public Dbdao(Context context){
		super(context, DBNAME, null, DBVERSION);
	}
	
	@Override
	public void onCreate(SQLiteDatabase db) {
		// TODO Auto-generated method stub
		String sql =" CREATE TABLE "+ TABNAME+" (" +
		" id INTEGER ," +
		" score INTEGER "+
				") ";
		db.execSQL(sql);
	}
	
	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		// TODO Auto-generated method stub
		String sql = " DROP TABLE IF EXISTS " + TABNAME;
		db.execSQL(sql);
		this.onCreate(db);
	}
	
	public void insert(Integer score){
		SQLiteDatabase db = getWritableDatabase();
		ContentValues values = new ContentValues();
		values.put("id", 1);
		values.put("score", score);
		db.insert(TABNAME, null, values);
		db.close();
	}
	
	public void delete(){
		SQLiteDatabase db = getWritableDatabase();
		String[] data = new String[1]; 
		data[0] = "1";
		db.delete(TABNAME,"id = ?",data);
		db.close();
	}
	
	public Integer query(){
		SQLiteDatabase db = getWritableDatabase();
		Cursor c = db.query(TABNAME, null, null, null, null, null, null); 
		c.moveToFirst();
		int index = c.getColumnIndex("score");
		String result = c.getString(index);
		db.close();
		return Integer.valueOf(result);
	}

}