DBHelper.java

package com.momo.mvp_demo;

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

/**
 * Created by RealMo on 2016-12-23.
 */
public class DBHelper extends SQLiteOpenHelper {
 private final static String DBNAME = "my.db";
 private final static String USER = "user";
 private final static String FOOD = "food";
 private final static String PERSON = "person";
 private final static int STARTVERSION = 1;
 private final static int CURRENTVERSION = 3;


 public DBHelper(Context context) {
 super(context, DBNAME, null, CURRENTVERSION);
 }

 @Override
 public void onCreate(SQLiteDatabase db) {
 db.execSQL("CREATE TABLE IF NOT EXISTS " + USER + "(_id INTEGER PRIMARY KEY AUTOINCREMENT,USERNAME,PASSWORD)");
 onUpgrade(db, STARTVERSION, CURRENTVERSION);
 }

 @Override
 public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
 switch (oldVersion) {
 case 1:
 //添加FOOD
 db.execSQL("CREATE TABLE IF NOT EXISTS " + FOOD + "(_id INTEGER PRIMARY KEY AUTOINCREMENT,USERNAME,PASSWORD)");
 case 2:
 //添加PERSON
 db.execSQL("CREATE TABLE IF NOT EXISTS " + PERSON + "(_id INTEGER PRIMARY KEY AUTOINCREMENT,USERNAME,PASSWORD)");
 break;
 }
 }
}