数据库SQLite

public class MySQLite extends SQLiteOpenHelper {
        private final String create_book = "create table book " + "(id integer primary key autoincrement, "            + "price real, name text, " + "author text, pages integer)";    private final String create_category = "create table category " + "(id integer primary key autoincrement, "            + "category_name text, category_code integer)";    Context ctx;    public MySQLite(Context context, String name, CursorFactory factory, int version) {
            super(context, name, factory, version);        ctx = context;    }    @Override    public void onCreate(SQLiteDatabase db) {
            db.execSQL(create_book);        db.execSQL(create_category);        Toast.makeText(ctx, "Create DB", Toast.LENGTH_SHORT).show();    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            switch (oldVersion) {
            case 1:            db.execSQL(create_category);        case 2:            db.execSQL("alter table book add column category_code integer");        default:            break;        }    }}

增删改查操作：

public class MainActivity extends Activity {
        SQLiteDatabase db;    @Override    protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Button btn = (Button) findViewById(R.id.btn);        db = new MySQLite(MainActivity.this, "test", null, 2).getWritableDatabase();        btn.setOnClickListener(new OnClickListener() {
                @Override            public void onClick(View v) {
                    // db = new MySQLite(MainActivity.this, "test", null, 2).getWritableDatabase();            }        });        // 增        Button add_btn = (Button) findViewById(R.id.add_btn);        add_btn.setOnClickListener(new OnClickListener() {
                @Override            public void onClick(View v) {
                    ContentValues values = new ContentValues();                values.put("price", 10.00);                values.put("name", "from A to Z");                values.put("author", "lwt");                values.put("pages", 300);                db.insert("book", null, values);                values.clear();                values.put("price", 60.00);                values.put("name", "麦琪的礼物");                values.put("author", "欧亨利");                values.put("pages", 255);                db.insert("book", null, values);            }        });        // 改        Button edit_btn = (Button) findViewById(R.id.edit_btn);        edit_btn.setOnClickListener(new OnClickListener() {
                @Override            public void onClick(View v) {
                    ContentValues values = new ContentValues();                values.put("price", 23.00);                db.update("book", values, "name=?", new String[] {
     "麦琪的礼物" });            }        });        // 删        Button del_btn = (Button) findViewById(R.id.del_btn);        del_btn.setOnClickListener(new OnClickListener() {
                @Override            public void onClick(View v) {
                    db.delete("book", "id in (? , ?)", new String[] {
     "1", "2" });            }        });        // 查        Button sel_btn = (Button) findViewById(R.id.sel_btn);        sel_btn.setOnClickListener(new OnClickListener() {
                @Override            public void onClick(View v) {
                    Cursor cursor = db.query("book", null, null, null, null, null, null);                if (cursor.moveToFirst()) {
                        do {
                            String name = cursor.getString(cursor.getColumnIndex("name"));                        String author = cursor.getString(cursor.getColumnIndex("author"));                        Integer pages = cursor.getInt(cursor.getColumnIndex("pages"));                        Double price = cursor.getDouble(cursor.getColumnIndex("price"));                        Log.d("debug",                                String.format("name: %s, author: %s, pages: %d, price:%f", name, author, pages, price));                    } while (cursor.moveToNext());                }                cursor.close();            }        });    }}

或直接用语句：

db.execSQL("insert into book (name, author, price, pages) values (?, ?, ?, ?)",         new String[]{
    "name", "author", "10.11", "234"});db.execSQL("delete from book where name = ?", new String[]{
    "lwt"});db.execSQL("update book set price = ? where name = ?", new String[]{
    "99.99", "lwt"});db.rawQuery("select * from book", null);

用adb命令行查看表：

adb shell #进入shellcd data/data/com.example.testsqlite/databases #进入数据库所在目录sqlite3 test #进入数据库.table   #显示表.schame  #显示建表语句.exit    #退出