在Android中使用數據庫時,會建立一個類繼承SQLiteOpenHelper類,在這個類封裝數據的增刪改查操做,本身寫了一個複習了一下sql
- /**
- * @auther xiang1988
- * @param pacageName 程序包名
- * @param dbName 數據庫的名字
- * @return
- */
- public static boolean databaseExist(String pacageName,String dbName) {
- File dbFile = new File("/data/data/"+pacageName+"/databases/"+dbName+".db");
- return dbFile.exists();
- }
- /**
- *數據庫操做類
- **/
- public class MyDBHelper extends SQLiteOpenHelper {
- private static final String TB_NAME = "TimeTB";
- private SQLiteDatabase dataBase;
- public MyDBHelper(Context context, String name, CursorFactory factory,
- int version) {
- super(context, name, factory, version);
- // TODO Auto-generated constructor stub
- }
- @Override
- public void onCreate(SQLiteDatabase db) {
- // TODO Auto-generated method stub
- /**
- * 進行建立表的操做
- *
- */
- String sql = "create table " +TB_NAME+" ( id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR(36), time INTEGER)";
- db.execSQL(sql);
- }
- @Override
- public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
- // TODO Auto-generated method stub
- /**
- * 進行數據庫的升級操做
- *
- */
- }
- /**
- * 開啓數據庫
- */
- public void openDB(){
- //此處獲取數據的操做,若是數據庫存在,則拿到引用,若是不存在,就會建立一個空白的數據庫
- dataBase=getWritableDatabase();
- }
- /**
- * 關閉數據
- */
- public void closeDB(){
- dataBase.close();
- }
- /**
- * 插入數據
- * @param name
- * @param time
- */
- public void insertData(String name,int time){
- ContentValues value=new ContentValues();
- value.put("name", name);
- value.put("time", time);
- dataBase.insert(TB_NAME, null, value);
- }
- /**
- * 刪除數據數據
- * @param name
- * @param time
- */
- public void deleteDataByName(String name){
- dataBase.delete(TB_NAME, "name =?", new String[]{name});
- }
- /**
- * 一個查詢數據庫的操做
- * @return
- */
- public ArrayList<Integer> queryData() {
- SQLiteDatabase db = getWritableDatabase();
- ArrayList<Integer> list = new ArrayList<Integer>();
- Cursor cursor = db.query(TB_NAME, new String[] { "time" }, null, null,
- null, null, null);
- cursor.moveToNext();
- while (cursor.moveToNext()) {
- list.add(cursor.getInt(cursor.getColumnIndex("time")));
- }
- cursor.close();
- db.close();
- return list;
- }
- }