數(shù)據(jù)庫(kù)

• 第一步
  創(chuàng)建一個(gè)新工程净薛，創(chuàng)建一個(gè)class這個(gè)class繼承于SQLiteOpenHelper這個(gè)類，并實(shí)現(xiàn)兩個(gè)方法和一個(gè)構(gòu)造方法

• 第二步：調(diào)用SQLiteOpenHelper這個(gè)類的構(gòu)造方法啊胶，先創(chuàng)建一個(gè)對(duì)象，然后調(diào)用創(chuàng)建數(shù)據(jù)庫(kù)的方法 參數(shù)1：許你一個(gè)上下文 參數(shù)2：數(shù)據(jù)庫(kù)名稱 參數(shù)3：null 參數(shù)四：不能小于1垛贤；
  MyOpenHelper oh = new MyOpenHelper(getContext(), "people.db", null, 1);
  SQLiteDatabase db = oh.getWritableDatabase();//如果數(shù)據(jù)庫(kù)不存在创淡，先創(chuàng)建數(shù)據(jù)庫(kù) ，獲取一個(gè)可讀可寫數(shù)據(jù)庫(kù)對(duì)象

• 第三步：創(chuàng)建數(shù)據(jù)庫(kù)表
  @Override
  public void onCreate(SQLiteDatabase arg0) {
  //創(chuàng)建數(shù)據(jù)庫(kù)表
  arg0.execSQL("create table person(_id integer primary key autoincrement, name char(10),salary char(20),phone integer(20) )");
  }

• 第四步：創(chuàng)建表之后就可以進(jìn)行表的增刪改查了
  public void insert(){
  MyOpenHelper oh = new MyOpenHelper(getContext(), "people.db", null, 1);
  SQLiteDatabase db = oh.getWritableDatabase();
  db.execSQL("insert into person(name,salary,phone)values(?,?,?)", new Object[]{"小志志卡","13000",138438});
  db.close();
  }
  public void delete(){
  MyOpenHelper oh = new MyOpenHelper(getContext(), "people.db", null, 1);
  SQLiteDatabase db = oh.getWritableDatabase();
  db.execSQL("delete from person where name = ?", new Object[]{"小志"});
  db.close();
  }

  public void updata(){
  MyOpenHelper oh = new MyOpenHelper(getContext(), "people.db", null, 1);
  SQLiteDatabase db = oh.getWritableDatabase();
  db.execSQL("update person set phone = ? where name = ?", new Object[]{123,"小志志卡"});
  db.close();
  }

• 上面的方法容易出錯(cuò)南吮，可以用封裝好的api來進(jìn)行增刪改查
  public void deleteApi(){
  MyOpenHelper oh = new MyOpenHelper(getContext(), "people.db", null, 1);
  SQLiteDatabase db = oh.getWritableDatabase();
  int i = db.delete("person", "name = ?", new String[]{"游天龍"});
  db.close();
  }

  public void updateApi(){
  ContentValues values = new ContentValues();
  values.put("salary", 1300);
  MyOpenHelper oh = new MyOpenHelper(getContext(), "people.db", null, 1);
  SQLiteDatabase db = oh.getWritableDatabase();
  db.update("person", values, "name = ?", new String[]{"游天龍"});
  db.close();
  }

  public void selectApi(){
  ContentValues values = new ContentValues();
  values.put("salary", 1300);
  MyOpenHelper oh = new MyOpenHelper(getContext(), "people.db", null, 1);
  SQLiteDatabase db = oh.getWritableDatabase();
  Cursor cursor = db.query("person", null, null, null, null, null, null, null);
  while (cursor.moveToNext()) {
  String name = cursor.getString(cursor.getColumnIndex("name"));
  String phone = cursor.getString(cursor.getColumnIndex("phone"));
  String salary = cursor.getString(cursor.getColumnIndex("salary"));
  }
  db.close();
  }

• 事務(wù)：要成功一起成功，要失敗都失敗
  public void transaction(){
  MyOpenHelper oh = new MyOpenHelper(getContext(), "people.db", null, 1);
  SQLiteDatabase db = oh.getWritableDatabase();

    db.beginTransaction();
    ContentValues values = new ContentValues();
    values.put("salary", 12000);
    db.update("person", values, "name = ?", new String[]{"小志卡"});
    
    values.clear();
    values.put("salary", 14000);
    db.update("person", values, "name = ?", new String[]{"小志志卡"});
    db.setTransactionSuccessful();
    db.endTransaction();
    db.close();
}