数据库的增删查改

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package com.example.xiangmu.dbhelper;

import java.util.ArrayList;
import java.util.Currency;
import java.util.List;

import com.example.xiangmu.vo.Person;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

public class Dbmanager {
   Sqlhelper helper;
   SQLiteDatabase db;
   public Dbmanager(Context context) {
       super();
       helper=new Sqlhelper(context);
       db=helper.getWritableDatabase();
   }

   //添加方法
   public void add(List<Person> persons){
       for(Person person:persons){
           ContentValues values=new ContentValues();
           values.put("name", person.name);
           values.put("age", person.age);
           values.put("address", person.address);
           db.insert("ren", null, values);
       }

   }

   //查询地方法
   public List<Person> select(){
       List<Person> persons=new ArrayList<Person>();
       Cursor cursor=db.query("ren", new String []{"_id","name","age","address"}, null, null, null, null, null);
       while(cursor.moveToNext()){
           Person person=new Person();
           person.id=cursor.getInt(cursor.getColumnIndex("_id"));
           person.name=cursor.getString(cursor.getColumnIndex("name"));
           person.age=cursor.getInt(cursor.getColumnIndex("age"));
           person.address=cursor.getString(cursor.getColumnIndex("address"));
           persons.add(person);
       }

       return persons;
   }

   //删除方法
   public void delete(int id){
       db.delete("ren", "_id = ? ", new String []{String.valueOf(id)});
   }

   //更新
   public void update(String name,String address){
       ContentValues values=new ContentValues();
       values.put("address", address);
       db.update("ren", values, "name = ?", new String []{name});
   }
}

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