SQLite手機本地輕量級數(shù)據(jù)庫

數(shù)據(jù)庫分為：
1.關(guān)系型數(shù)據(jù)庫(mysql主外鍵屬于關(guān)系型)
2.對象型數(shù)據(jù)庫(oracle)
3.嵌入式數(shù)據(jù)庫


案例：
安卓控件(5個Button)訪問Activity訪問DBHelper返回Activity（處理后返回結(jié)果到控制臺）

SqlActivity類：

public class SqlActivity extends Activity {private Button buttonz;private Button buttons;private Button buttong;private Button buttonc;private DBHelper dbHelper;@Overrideprotected void onCreate(@Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);super.setContentView(R.layout.sql1);//綁定控件buttonz=findViewById(R.id.buttonz);buttonz.setOnClickListener(new MyInsertListener());buttons=findViewById(R.id.buttons);buttons.setOnClickListener(new MyDeleteListener());buttong=findViewById(R.id.buttong);buttong.setOnClickListener(new MyUpdateListener());buttonc=findViewById(R.id.buttonc);buttonc.setOnClickListener(new MyQueryListener());//創(chuàng)建數(shù)據(jù)庫dbHelper= new DBHelper(SqlActivity.this,"yuehui.db",null,1);System.out.println("創(chuàng)建了數(shù)據(jù)庫");}//增加數(shù)據(jù)class MyInsertListener implements View.OnClickListener{@Overridepublic void onClick(View v) {//獲取數(shù)據(jù)庫信息SQLiteDatabase db = dbHelper.getWritableDatabase();//操作數(shù)據(jù)庫db.execSQL("insert into qingyou(name,age) values(?,?)",new Object[]{"jw",18});System.out.println("增加了數(shù)據(jù)");//關(guān)閉資源db.close();}}//刪除數(shù)據(jù)class MyDeleteListener implements View.OnClickListener{@Overridepublic void onClick(View v) {//獲取數(shù)據(jù)庫信息SQLiteDatabase db = dbHelper.getReadableDatabase();//操作數(shù)據(jù)庫db.execSQL("delete from qingyou where id=?",new Object[]{2});System.out.println("刪除了數(shù)據(jù)");//關(guān)閉資源db.close();}}//修改數(shù)據(jù)class MyUpdateListener implements View.OnClickListener{@Overridepublic void onClick(View v) {//獲取數(shù)據(jù)庫信息SQLiteDatabase db = dbHelper.getWritableDatabase();//操作數(shù)據(jù)庫db.execSQL("update qingyou set name=? where id=?",new Object[]{"jiangwei",2});System.out.println("修改了數(shù)據(jù)");//關(guān)閉資源db.close();;}}//查詢數(shù)據(jù)class MyQueryListener implements View.OnClickListener{@Overridepublic void onClick(View v) {//獲取數(shù)據(jù)庫信息SQLiteDatabase db = dbHelper.getReadableDatabase();//操作數(shù)據(jù)庫Cursor cursor =db.rawQuery("select * from qingyou",null);//循環(huán)遍歷獲取數(shù)據(jù)while(cursor.moveToNext()){int id =cursor.getInt(cursor.getColumnIndex("id"));String name=cursor.getString(cursor.getColumnIndex("name"));int age = cursor.getInt(cursor.getColumnIndex("age"));//輸出信息System.out.println(id+"\t"+name+"\t"+age);}//關(guān)閉資源cursor.close();;db.close();}} }

DBHelper類：
?

public class DBHelper extends SQLiteOpenHelper{//構(gòu)造方法public DBHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {super(context, name, factory, version);}@Overridepublic void onCreate(SQLiteDatabase db) {//創(chuàng)建表，如表已存在則不創(chuàng)建db.execSQL("create table qingyou(id integer primary key autoincrement,name String,age integer)");System.out.println("創(chuàng)建了表");}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {} }

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