Android数据存储和访问之SQLite存储

来源：互联网发布：珠光宝气人物分析知乎编辑：程序博客网时间：2024/05/14 20:07

上一篇已经讲到如何使用adb查询表结构的建立接下来就介绍实现的几中操作

SQLite数据库简介

ACID;数据库事物正确执行的4个基本要素：

1：原子性2：一致性3：隔离性4:持久性

数据的常用操作主要有以下：

1、创建数据库：

2、添加数据库

 public  void addData(View view){        SQLiteDatabase sqLiteDatabase=dbHelper.getWritableDatabase();        ContentValues contentValues=new ContentValues();//封装数据       //开始组装第一条数据        contentValues.put("name","Java");        contentValues.put("author","孙卫琴");        contentValues.put("pages","500");        contentValues.put("price","56.5");        sqLiteDatabase.insert("book","name",contentValues);        //insert  into book(name) values(null);        contentValues.put("name","c++");        contentValues.put("author","Dan");        contentValues.put("pages","400");        contentValues.put("price","56");        sqLiteDatabase.insert("book","name",contentValues);    }

3、删除数据

public  void deleteData(View view){        SQLiteDatabase sqLiteDatabase=dbHelper.getWritableDatabase();        sqLiteDatabase.delete("book","pages<?",new String[]{"500"});    }

4、更新数据

public  void queryData(View view){    StringBuilder stringBuilder=new StringBuilder();    SQLiteDatabase sqLiteDatabase=dbHelper.getWritableDatabase();    Cursor cursor=sqLiteDatabase.query("Book",null,null,null,null,null,null);    if(cursor.moveToFirst()){        do{            String name=cursor.getString(cursor.getColumnIndex("name"));            String author=cursor.getString(cursor.getColumnIndex("author"));            int pages=cursor.getInt(cursor.getColumnIndex("pages"));            double  price=cursor.getDouble(cursor.getColumnIndex("price"));            stringBuilder.append(name+"-"+author+"-"+pages+"-"+price+"\n");        }while(cursor.moveToNext());    }

在DBhelper类中

package cn.edu.bzu.sqlapplication.db;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import android.util.Log;import android.widget.Toast;public class DBHelper extends SQLiteOpenHelper{//vesion 数据库名称    private  Context context;    public  static  final String DB_NAME="BookStore.db";    public  static  final String CREATE_BOOK="create table book(id integer primary key autoincrement,author text,price real,pages integer,name text)";    public  static  final String CREATE_CATEGORY="create table category(id integer primary key autoincrement,name text, code integer)";    public DBHelper(Context context,int version) {        super(context,DB_NAME,null, version);        Log.d("DBHelper","constructor");        this.context=context;    }    @Override    public void onCreate(SQLiteDatabase db) {        Log.d("DBHelper","onCreate");       db.execSQL(CREATE_BOOK);        db.execSQL(CREATE_CATEGORY);        Toast.makeText(context,"create succeeded",Toast.LENGTH_LONG).show();    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {           db.execSQL("drop table if exists book");        db.execSQL("drop table if exists category");        onCreate(db);    }}

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