Android 数据库管理— — —更新数据

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <Button
        android:id="@+id/create_database"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="创建数据库"
        android:layout_marginTop="10dp"
        />

    <Button
        android:id="@+id/add_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="添加数据"
        android:layout_marginTop="10dp"
        />

    <Button
        android:id="@+id/update_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="更新数据"
        android:layout_marginTop="10dp"
        />
</LinearLayout>

package com.example.datebasetest;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;

/**
 * Created by Administrator on 2016/3/4.
 */
public class DatabaseHelper extends SQLiteOpenHelper{

    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,category_name text,category_code integer)";
    private Context mContext;

    public DatabaseHelper(Context context, String name, CursorFactory factory, int version) {
        super(context, name, factory, version);
        mContext = context;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_BOOK);
        db.execSQL(CREATE_CATEGORY);
        Toast.makeText(mContext,"创建成功",Toast.LENGTH_SHORT).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);
    }

}

package com.example.datebasetest;

import android.content.ContentValues;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    private Button btn;
    private DatabaseHelper dbHelper;
    private Button addButton;
    private Button updateData;

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

        btn = (Button)findViewById(R.id.create_database);
        dbHelper = new DatabaseHelper(this,"BookStore.db",null,2);
        addButton = (Button)findViewById(R.id.add_data);
        updateData = (Button)findViewById(R.id.update_data);

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dbHelper.getWritableDatabase();
            }
        });

        addButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                ContentValues values = new ContentValues();
                values.put("name","wz");
                values.put("author","xx");
                values.put("price",1.0);
                values.put("pages",156);
                db.insert("Book",null,values);
                values.clear();
                values.put("name","wz2");
                values.put("author","xx2");
                values.put("price",2.0);
                values.put("pages",122);
                db.insert("Book",null,values);

            }
        });

        updateData.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                ContentValues values = new ContentValues();
                values.put("price",10.99);
                db.update("Book",values,"name=?",new String[]{"wz"});
            }
        });
    }
}