数据存储和访问—数据的增删改查

方法一、命令行模式。在环境变量Path中配置Platform-tools的路径，输入   adb shell，输入   cd /data/data/cn.bzu.tong.sqlite/databases，输入    sqlite3 BookStore.db，输入 .table查看数据库中的表，输入.scheme,查看建表语句，输入 select * from Book查看表中内容（自己运行显示不出内容）。

方法二、Navicat模式。模拟器运行，点击Create database等按钮，每一次都将模拟器中的BookStore.db导出，在Navicat中新建连接后导入该数据库，打开book表查看表中信息。

一、运行效果

1、Create databases

2、Add data   添加数据

3、Update data    更新数据

4、Delete Data    删除数据

5、Quary data    查询数据

Logcat显示如下图：

7、模拟器界面MainActivity.xml

二、核心代码

MainActivity.java

 package cn.bzu.tong.sqlite;

 import android.app.Activity;
 import android.content.ContentValues;
 import android.database.Cursor;
 import android.database.sqlite.SQLiteDatabase;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.Menu;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;
 import cn.bzu.tong.sqlist.R;
 import cn.bzu.tong.sqlite.db.DBHelper;

 public class MainActivity extends Activity {

     private DBHelper dbHelper;
     private Button createDatabase,addData,updateData,deleteData,queryData;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         dbHelper = new DBHelper(this,"BookStore.db",null, 2);
         queryData = (Button) findViewById(R.id.query_data);
         deleteData = (Button) findViewById(R.id.delete_data);
         updateData = (Button) findViewById(R.id.update_data);
         addData = (Button) findViewById(R.id.add_data);
         createDatabase = (Button) findViewById(R.id.creat_database);
         createDatabase.setOnClickListener(new OnClickListener() {

             @Override
             public void onClick(View view) {

                 dbHelper.getWritableDatabase();
             }
         });
         addData.setOnClickListener(new OnClickListener() {

             @Override
             public void onClick(View view) {

                 SQLiteDatabase db = dbHelper.getWritableDatabase();
                 ContentValues values = new ContentValues();
                 //开始组装第一条数据
                 values.put("name", "The Da Vinci Code");
                 values.put("author", "Dan Brown");
                 values.put("pages", 454);
                 values.put("price", 16.96);
                 db.insert("Book", null, values);//插入第一条数据
                 values.clear();
                 //开始组装第二条数据
                 values.put("name", "The Lost Symbol");
                 values.put("author", "Dan Brown");
                 values.put("pages", 510);
                 values.put("price", 19.95);
                 db.insert("Book", null, values);//插入第二条数据
             }
         });
         updateData.setOnClickListener(new OnClickListener() {

             @Override
             public void onClick(View view) {

                 SQLiteDatabase db = dbHelper.getWritableDatabase();
                 ContentValues values = new ContentValues();
                 values.put("price", 10.99);
                 db.update("Book", values, "name=?", new String[]{"The Da Vinci Code"});
             }
         });
         deleteData.setOnClickListener(new OnClickListener() {

             @Override
             public void onClick(View view) {

                 SQLiteDatabase db = dbHelper.getWritableDatabase();
                 db.delete("Book", "pages > ?", new String[]{"400"});//范围
             }
         });
         queryData.setOnClickListener(new OnClickListener() {

             @Override
             public void onClick(View view) {

                 SQLiteDatabase db = dbHelper.getWritableDatabase();
                 //查询Book表中所有数据
                 Cursor cursor = db.query("Book",null,null,null,null,null,null);
                 if(cursor.moveToFirst()){
                     do{
                         //遍历Cursor对象，取出数据并打印
                         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"));
                         Log.d("MainActivity", "book name is "+name);
                         Log.d("MainActivity", "book author is "+author);
                         Log.d("MainActivity", "book page is "+pages);
                         Log.d("MainActivity", "book price is "+price);

                     }while(cursor.moveToNext());
                 }
                 cursor.close();
             }
         });
     }


     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         // Inflate the menu; this adds items to the action bar if it is present.
         getMenuInflater().inflate(R.menu.main, menu);
         return true;
     }

 }

DBHelper.java

 package cn.bzu.tong.sqlite.db;

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

 public class DBHelper extends SQLiteOpenHelper {

     public static final String CREATE_TABLE_BOOK = "create table book("
             + "id integer primary key autoincrement," + "author text,"
             + "price real," + "pages integer," + "name text)";
     private Context mContext;

     public static final String CREATE_TABLE_CATEGORY="create table Category(id integer primary key autoincrement," +
             "category_name text,category_code integer)";
     public DBHelper(Context context, String name, CursorFactory factory,
             int version) {
         super(context, name, factory, version);
         mContext = context;
     }

     @Override
     public void onCreate(SQLiteDatabase db) {

         db.execSQL(CREATE_TABLE_BOOK);
         db.execSQL(CREATE_TABLE_CATEGORY);
         Toast.makeText(mContext, "create succeeded", 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);
     }

 }

activity_main.xml

 "http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     tools:context=".MainActivity"
     android:orientation="vertical" >


         android:id="@+id/creat_database"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:text="Create database" />

         android:id="@+id/add_data"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:text="Add Data"/>

         android:id="@+id/update_data"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:text="Update Data"/>

         android:id="@+id/delete_data"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:text="Delete Data"/>

         android:id="@+id/query_data"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:text="Query Data"/>