第一步、数据库初始化

继承 SQLiteOpenHelper,初始化数据库

public class MyOpenHelper extends SQLiteOpenHelper {  

    public MyOpenHelper(Context context) {  
        super(context, "itheima.db", null,4);  
    } 
    /** 
     * Called when the database is created for the first time. 
     * 当数据库第一次创建的时候调用 
     * 那么这个方法特别适合做表结构的初始化  创建表就是写sql语句 
     */  
    @Override  
    public void onCreate(SQLiteDatabase db) {  

        //id 一般以_id 
        db.execSQL("create table info(_id integer primary key autoincrement,name varchar(20),phone varchar(20))"); 
    }  
    /** 
     * Called when the database needs to be upgraded 
     * 当数据库版本升级的时候调用 
     * 这个方法适合做   表结构的更新 
     */  
    @Override  
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
        db.execSQL("alter table info add phone varchar(20)");       
    }   
}  

第二步、数据库的增删改查

public class MainActivity extends Activity {  
  
    private MyOpenHelper myOpenHelper;  

    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
          
        myOpenHelper = new MyOpenHelper(getApplicationContext());  
          
        //打开或者创建数据库  如果是第一次就是创建     
//      SQLiteDatabase sqLiteDatabase = myOpenHelper.getWritableDatabase();  
        //打开或者创建数据库  如果是第一次就是创建     如果磁盘满了 返回只读的  
//      SQLiteDatabase readableDatabase = myOpenHelper.getReadableDatabase();     
    } 
    //点击按钮增加一条记录  
    public void click1(View v){  
        //[1]获取数据库对象  
        SQLiteDatabase db = myOpenHelper.getWritableDatabase();  
        //[2]执行增加一条的sql语句   
        db.execSQL("insert into info(name,phone) values(?,?)", new Object[]{"张三","1388888"});  
        //[3]数据库用完需要关闭  
        db.close();    
    } 
     
    //删除  
    public void click2(View v){  
        SQLiteDatabase db = myOpenHelper.getWritableDatabase();  
        db.execSQL("delete from info where name=?", new Object[]{"张三"});  
        db.close();    
    }
    //更新   
    public void click3(View v){  
        SQLiteDatabase db = myOpenHelper.getWritableDatabase();  
        db.execSQL("update info set phone=? where name=? ", new Object[]{"138888888","张三"});  
        db.close();  
    } 
    //查找  
    public void click4(View v){  
          
        SQLiteDatabase db = myOpenHelper.getReadableDatabase();  
  
        Cursor cursor = db.rawQuery("select * from info", null);  
        if (cursor!= null&&cursor.getCount()>0) {  
            while(cursor.moveToNext()){  
                //columnIndex代表列的索引   
                String name = cursor.getString(1);  
                String phone = cursor.getString(2);  
                System.out.println("name:"+name+"----"+phone);  
                }}}}