手机数据的增删改查及版本升级

.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.hanqi.test5.dataActivity2"
    android:orientation="vertical">

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="创建数据库"
        android:id="@+id/bt_11"
        android:onClick="bt11_onClick"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="升级数据库"
        android:id="@+id/bt_12"
        android:onClick="bt12_onClick"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="增加数据"
        android:id="@+id/bt_13"
        android:onClick="bt13_onClick"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="删除数据"
        android:id="@+id/bt_14"
        android:onClick="bt14_onClick"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="修改数据"
        android:id="@+id/bt_15"
        android:onClick="bt15_onClick"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="查询数据"
        android:id="@+id/bt_16"
        android:onClick="bt16_onClick"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="事务操作"
        android:id="@+id/bt_17"
        android:onClick="bt17_onClick"/>



</LinearLayout>

.java

package com.hanqi.test5;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Toast;

public class dataActivity2 extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_data2);
    }

    //继承SQLiteOpenHelper
    class DBHelper extends SQLiteOpenHelper {

        //构造方法
        //name 数据库名
        //version  创建的数据库版本号
        public DBHelper(String name, int version) {

            //写在第一行
            super(dataActivity2.this, name, null, version);
        }

        //回调方法
        //在创建数据库时调用
        //什么时候创建数据库：连接数据库的时候如果数据文件不存在
        //只调用一次
        @Override
        public void onCreate(SQLiteDatabase db) {

            //1.创建数据库
            String creatTable = "create table user (_id integer PRIMARY KEY AUTOINCREMENT NOT NULL,name varchar,age int)";
            db.execSQL(creatTable);

            //2.初始化数据
            ContentValues cv = new ContentValues();

            cv.put("name","元芳");
            cv.put("age", 139);

            //如果不成功会返回 —1
            //1-表名
            //2-空列的默认值
            //3-字段和值的key/value集合
         long l = db.insert("user",null,cv);



            Toast.makeText(dataActivity2.this, "id =" + l, Toast.LENGTH_SHORT).show();
        }

        //升级数据库
        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

            //执行升级
            //update user set age = 30 where _id = ?
            //? 是占位符，然后给占位符赋值

            ContentValues cv = new ContentValues();

            cv.put("age", 14);
           int rowcount = db.update("user", cv, "_id=? and name=?", new String[]{"1", "tpm"});

            Log.e("TAG", "rowcount=" + rowcount);


        }
    }

    //创建数据库
    public void bt11_onClick(View v)
    {
      //创建
        DBHelper dh = new DBHelper("test.db",1);

        //获取数据库实例
        SQLiteDatabase sd = dh.getWritableDatabase();

        sd.close();
    }

    //升级数据库
    public void bt12_onClick(View v)
    {
        //创建  实现工具类
        DBHelper dh = new DBHelper("test.db",2);

        //获取数据库实例
        SQLiteDatabase sd = dh.getWritableDatabase();

        sd.close();
    }

    //插入数据
    public void bt13_onClick(View v)
    {
        //创建
        DBHelper dh = new DBHelper("test.db",2);

        //获取数据库实例
        SQLiteDatabase sd = dh.getWritableDatabase();

        ContentValues cv = new ContentValues();

        cv.put("name","吴元芳");
        cv.put("age", 19);

        long _id = sd.insert("user", null, cv);
        Log.e("TAG","_id ="+ _id);

        sd.close();
    }

    //查询
    public void bt16_onClick(View v)
    {
        //创建
        DBHelper dh = new DBHelper("test.db",2);

        //获取数据库实例
        SQLiteDatabase sd = dh.getWritableDatabase();

        //全表查询
        //返回游标
        Cursor cursor = sd.query("user", null, null, null, null, null, null);

        //Cursor一开始会定位在第一条数据的上方
        //移动游标到数据的上面，提取数据后，再继续移动
        while (cursor.moveToNext())
        {
            long _id = cursor.getInt(cursor.getColumnIndex("_id"));
            String name = cursor.getString(1);
            int age = cursor.getInt(2);

            Log.e("TAG","id ="+_id +"name ="+name+"age ="+age);
            cursor.close();

            sd.close();
        }
    }

    //修改
    public void bt15_onClick(View v)
    {
        //创建
        DBHelper dh = new DBHelper("test.db",2);

        //获取数据库实例
        SQLiteDatabase sd = dh.getWritableDatabase();

        ContentValues cv = new ContentValues();

        cv.put("name","吴元芳");


        int count = sd.update("user", cv, "_id >= 3", null);

        Log.e("TAG","updatecount ="+ count);

        sd.close();
    }

    //删除
    public void bt14_onClick(View v)
    {
        //创建
        DBHelper dh = new DBHelper("test.db",2);

        //获取数据库实例
        SQLiteDatabase sd = dh.getWritableDatabase();


        int count = sd.delete("user", "_id = 3", null);

        Log.e("TAG","deletecount ="+ count);

        sd.execSQL("delete from user where _id = 5");

        sd.close();
    }

    //事务操作
    public void bt17_onClick(View v)
    {
        //创建
        DBHelper dh = new DBHelper("test.db",2);

        //获取数据库实例
        SQLiteDatabase sd = dh.getWritableDatabase();

        //连接
        //sd = SQLiteDatabase.openOrCreateDatabase("test.db",null);
        //判断是否建表了，是否升级了

        try {

            //一·开启事务
            sd.beginTransaction();

            ContentValues cv = new ContentValues();

            cv.put("age", "45");


            int count = sd.update("user", cv, "_id = 3", null);

            //抛出异常
            boolean b = true;
            if (b) {
                throw new RuntimeException("出现异常了");
            }

            count += sd.update("user", cv, "_id = 6", null);

            Log.e("TAG", "updatecount =" + count);

            //二·设置事务执行成功

            sd.setTransactionSuccessful();
        }
        catch (Exception e)
        {
            e.printStackTrace();
            Toast.makeText(dataActivity2.this, e.getMessage(), Toast.LENGTH_SHORT).show();
        }
        finally {
            //三·结束事务，1）提交；2）回滚；
            sd.endTransaction();

            sd.close();
        }

    }
}

操作效果图