sqlite数据库

MyDatabaseHelper.class

// [1] 创建一个类继承 SQLiteOpenHelperpublic class MyDatabaseHelper extends SQLiteOpenHelper {    public static final String CREATE_BOOK = "create table Book(" +            "id integer primary key autoincrement," +            "author text," +            "price real," +            "pages integer," +            "name text)";    public static final String CREATE_CATEGORY = "create table Category(" +            "id integer primary key autoincrement," +            "category_name text," +            "category_code integer)";    private Context context;    public MyDatabaseHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {        super(context, name, factory, version);        this.context = context;    }    @Override    public void onCreate(SQLiteDatabase db) {        // [2] 在OnCreate中执行语句        db.execSQL(CREATE_BOOK);        db.execSQL(CREATE_CATEGORY);        Toast.makeText(context, "创建成功", Toast.LENGTH_SHORT).show();    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {        //升级的时候将已经存在的表删除        db.execSQL("drop table if exists Book");        db.execSQL("drop table if exists Category");        onCreate(db);    }}

public void myClick(View view) {        /**         * 创建数据库         * @param 上下文         * @param 数据库文件名         * @param 游标工厂         * @param 数据库的版本 升级的时候要指定比之前更大的数值         */        dbHelper = new MyDatabaseHelper(this, "BookStore.db", null, 4);        // 获取数据库对象        db = dbHelper.getWritableDatabase();    }    // 增加    public void add(View view) {        db = dbHelper.getWritableDatabase();        // 创建values        ContentValues values = new ContentValues();        values.put("name", "alice in wonderland");        values.put("author", "lewis");        values.put("pages", 700);        values.put("price", 300.11);        db.insert("Book", null, values);        // 清空        values.clear();        // 往下继续插入        values.put("name", "One Hundred Years of Solitude");        values.put("author", "Gabriel");        values.put("pages", 500);        values.put("price", 100.11);        db.insert("Book", null, values);    }    // 修改    public void update(View view) {        db = dbHelper.getWritableDatabase();        ContentValues values = new ContentValues();        values.put("price",500.2);        db.update("Book",values,"name = ?",new String[]{"alice in wonderland"});    }    // 删除    public void del(View view) {        db = dbHelper.getWritableDatabase();        // 删除页数少于700的记录        db.delete("Book","pages = ?",new String[]{"700"});    }    // 查询    public void sel(View view){        StringBuilder sb = new StringBuilder();        db = dbHelper.getWritableDatabase();        Cursor cursor = db.query("Book", null, null, null, null, null, null);        // 将游标移到第一行        if(cursor.moveToFirst()){            do {                String name = cursor.getString(cursor.getColumnIndex("name"));                sb.append(name).append("\n");            } while (cursor.moveToNext()); // 将游标移到下一行,如果不存在返回false        }        cursor.close();        TextView mTv = (TextView) findViewById(R.id.textView);        mTv.setText(sb.toString());    }

也可以直接使用sql语句进行查询
如:
db.execSQL(“insert into Book (name,author) values(?,?)”,new String[]{“alice in wonderland”});
查询要使用rawQuery
如:
db.rawQuery(“select * from Book”,null);