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Android中数据库事务介绍

    事务概念

             在事务中包含的sql,要么同时执行成功 要么同时执行失败, 不能出现 部分成功部分失败的情况 典型案例 银行转账

     相关api

1. db.beginTransaction();//开启事务
2.   try {
3.     ...
4.     db.setTransactionSuccessful();//如果所有SQL都执行完毕则标记成功
5.   } finally {
6.     db.endTransaction();//如果有成功标记则关闭事务,没有成功标记回滚数据
7.   }

 

     具体代码

MyOpenHelper类

1. public class MyOpenHelper extends SQLiteOpenHelper {
2.    public MyOpenHelper(Context context) {
3.        super(context, "Account.db", null, 1);
4.    }
5.    @Override
6.    public void onCreate(SQLiteDatabase db) {
7.        db.execSQL("create table info (_id integer primary key autoincrement,name varchar(20),phone varchar(20),money varchar(20))");
8.        db.execSQL("insert into info ('name','phone','money') values ('张三','138888','2000')");
9.        db.execSQL("insert into info ('name','phone','money') values ('李四','139999','5000')");
10.    }
11.    @Override
12.    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
13.    }
14.}

 

MainActivity类

1. public class MainActivity extends Activity {
2.    private MyOpenHelper openHelper;
3.    @Override
4.    protected void onCreate(Bundle savedInstanceState) {
5.        super.onCreate(savedInstanceState);
6.        setContentView(R.layout.activity_main);
7.        //获取MyOpenHelper 用它可以获取SQLiteDatabase
8.        openHelper = new MyOpenHelper(this);
9.    }
10.   public void transaction(View v){
11.       SQLiteDatabase database = openHelper.getWritableDatabase();
12.       //开启事务
13.       database.beginTransaction();
14.       try {
15.           database.execSQL("update info set money= money-200 where name=?",new String[]{"张三"});
16.            //int i = 100/0;
17.           database.execSQL("update info set money= money+200 where name=?",new String[]{"李四"});
18.           //事务所有的sql执行成功之后 调用  setTransactionSuccessful 会加上一个标记说明事务成功执行了
19.           database.setTransactionSuccessful();
20.           } catch (Exception e) {
21.               Toast.makeText(getApplicationContext(), "服务器忙,请稍后再试", 0).show();
22.        }finally {
23.            //事务结束 会检查标记 如果没有成功标记则回滚 如果有成功标记则提交生效
24.               database.endTransaction();
25.           }
26.   }
27.}