public class MainActivity extends Activity {

     @Override

     protected void onCreate(Bundle savedInstanceState) {

         super.onCreate(savedInstanceState);

         setContentView(R.layout.activity_main);

         //每个程序都有自己的数据库 默认情况下是各自互不干扰

         //1.创建一个数据库并且打开

 SQLiteDatabase db=openOrCreateDatabase("user.db",MODE_PRIVATE,null);

 db.execSQL("create table if not exists usertb(_id integer primary key autoincrement," +

             "name text not null,age integer not null,sex text not null)");

         //创建用户表 包括 _id主键，姓名，年龄，性别

 db.execSQL("insert into usertb(name,age,sex)values('张三','男',26)");

 db.execSQL("insert into usertb(name,age,sex)values('刘明','男',22)");

 db.execSQL("insert into usertb(name,age,sex)values('于思','女',21)");

 //2.使用游标cursor相当于存储结果的集合，可理解为list

   Cursor c=db.rawQuery("select*from usertb",null);

   if(c!=null){

       while(c.moveToNext()){

           Log.i("info","_id:"+c.getInt(c.getColumnIndex("_id")));

           Log.i("info","name:"+c.getString(c.getColumnIndex("name")));

           Log.i("info","sex:"+c.getString(c.getColumnIndex("sex")));

           Log.i("info","age:"+c.getInt(c.getColumnIndex("age")));

           Log.i("info","!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");

       }

       c.close();//3.释放游标

   }

   db.close();

     }

 }