/**
* 银行转账操作
*/
public void transation(){
db.beginTransaction();
try {
//name为微明的用户向小红转账
ContentValues contentValues=new ContentValues();
contentValues.put("money", 1000);
db.update("person", contentValues, "name=?", new String[]{"微明"});
ContentValues contentValues2=new ContentValues();
contentValues2.put("money", 1100);
db.update("person", contentValues2, "name=?", new String[]{"小红"});
//全部语句运行完毕,若没有异常,则会运行这句设置事务成功的标记
db.setTransactionSuccessful();
} finally {
//会检查事务的标识,若没有调用setTransactionSuccessful()方法设置标志,则回滚事务。否则提交事务。
db.endTransaction();
}
}
}
MyOpenHelper.java
**SQLiteOpenHelper:
* A helper class to manage database creation and version management.
* 所以,SQLiteOpenHelper是对库本身的操作。若要对库中数据操作,须要使用库对象的方法。
*/
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class MyOpenHelper extends SQLiteOpenHelper {
//name:数据库文件的名字
//factory:游标工厂
//version:版本号,必须大于等于1
public MyOpenHelper(Context context, String name, CursorFactory factory, int version) {
super(context, name, factory, version);
// TODO Auto-generated constructor stub
}
//数据库创建时调用
@Override
public void onCreate(SQLiteDatabase db) {
//创建一个person表
db.execSQL("create table person(_id integer primary key autoincrement, name char(10), phone char(20))");
System.out.println("oncreate调用了");
}
//数据库升级时调用
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
System.out.println("onupgrade调用了");
db.execSQL("alter table person add money char(20)");
}
}
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