android 数据库 事务,Android开发之通过Android的API对sqlite数据库的操作以及数据库事务的练习...

packagecom.example.databasedemo;importandroid.content.ContentValues;importandroid.content.Context;importandroid.database.Cursor;importandroid.database.sqlite.SQLiteDatabase;importandroid.util.Log;/*** 这个类用于对数据库的增删改查*/

public classDao {private finalDatabaseHelper mHelper;private static final String TAG="Dao";publicDao(Context context){//创建数据库//Ctrl Alt F,之后加回车，创建成员变量

mHelper = newDatabaseHelper(context);

}public voidinsert(){

SQLiteDatabase db=mHelper.getWritableDatabase();//String sql="insert into " Constants.TABLE_NAME "(_id,name,age,salary,phone) values(?,?,?,?,?)";//Object []obj={1,"haohao",20,10000};//db.execSQL(sql,obj);

ContentValues values =newContentValues();//插入数据

values.put("_id",2);

values.put("name","me");

values.put("age",20);

values.put("salary",5);

db.insert(Constants.TABLE_NAME,null,values);

db.close();

}public voiddelete(){

SQLiteDatabase db=mHelper.getWritableDatabase();//String sql="delete from " Constants.TABLE_NAME " where name = ?";//Object []obj={"hao"};//db.execSQL(sql,obj);

int result = db.delete(Constants.TABLE_NAME, null, null);

Log.d(TAG,"result=" result);

db.close();

}public voidupdate(){

SQLiteDatabase db=mHelper.getWritableDatabase();//String sql="update " Constants.TABLE_NAME " set salary= ? where name = ?";//Object []obj={3,"hao"};//db.execSQL(sql,obj);

ContentValues values = newContentValues();

values.put("salary",54321);

db.update(Constants.TABLE_NAME,values,null,null);

db.close();

}public voidquery(){

SQLiteDatabase db=mHelper.getWritableDatabase();//String sql="select * from " Constants.TABLE_NAME " where name = ?";//String []obj={"hao"};//Cursor cursor = db.rawQuery(sql, obj);//while (cursor.moveToNext()){//String name = cursor.getString(cursor.getColumnIndex("name"));//String age = cursor.getString(cursor.getColumnIndex("age"));//Log.d(TAG,"名字：" name "年龄：" age);//}//cursor.close();

Cursor cursor= db.query(Constants.TABLE_NAME, null, null, null, null, null, null);while(cursor.moveToNext()){int id = cursor.getInt(0);

String name= cursor.getString(1);

Log.d(TAG,"ID=" id "name=" name);

}

cursor.close();

db.close();

}

}