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"});
}
});
}
}