增加删除修改查找

1.运行效果图：

2.代码如下：

MainActivity.java    package com.example.databasetest;    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.View;  import android.view.View.OnClickListener;  import android.widget.Button;    public class MainActivity extends Activity {        private MyDatabaseHelper dbHelper;        @Override      protected void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_main);          dbHelper = new MyDatabaseHelper(this, "BookStore.db", null, 2);            /* 创建数据 */          Button createDatabase = (Button) findViewById(R.id.create_database);          createDatabase.setOnClickListener(new OnClickListener() {              @Override              public void onClick(View v) {                  dbHelper.getWritableDatabase();              }          });            /* 添加数据 */          Button addData = (Button) findViewById(R.id.add_data);          addData.setOnClickListener(new OnClickListener() {              @Override              public void onClick(View v) {                  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              }          });            /* 更新数据 */          Button updateData = (Button) findViewById(R.id.update_data);          updateData.setOnClickListener(new 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[] { "The Da Vinci Code" });              }          });                    /*删除数据*/          Button deleteButton = (Button) findViewById(R.id.delete_data);          deleteButton.setOnClickListener(new OnClickListener() {              @Override              public void onClick(View v) {                  SQLiteDatabase db = dbHelper.getWritableDatabase();                  db.delete("Book", "pages > ?", new String[] { "500" });              }          });                    /*查询数据*/          Button queryButton = (Button) findViewById(R.id.query_data);          queryButton.setOnClickListener(new OnClickListener() {              @Override              public void onClick(View v) {                  SQLiteDatabase db = dbHelper.getWritableDatabase();                  // 查询Book表中所有的数据                  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 pages is " + pages);                          Log.d("MainActivity", "book price is " + price);                      } while (cursor.moveToNext());                  }                  cursor.close();              }          });      }    }    MydatabaseHelper.java    package com.example.databasetest;    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 MyDatabaseHelper 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 MyDatabaseHelper(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);          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      <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="Create database" />        <Button          android:id="@+id/add_data"          android:layout_width="match_parent"          android:layout_height="wrap_content"          android:text="Add data" />        <Button          android:id="@+id/update_data"          android:layout_width="match_parent"          android:layout_height="wrap_content"          android:text="Update data" />        <Button          android:id="@+id/delete_data"          android:layout_width="match_parent"          android:layout_height="wrap_content"          android:text="Delete data" />        <Button          android:id="@+id/query_data"          android:layout_width="match_parent"          android:layout_height="wrap_content"          android:text="Query data" />    </LinearLayout>      AndroidManifest.xml      <?xml version="1.0" encoding="utf-8"?>  <manifest xmlns:android="http://schemas.android.com/apk/res/android"      package="com.example.databasetest"      android:versionCode="1"      android:versionName="1.0" >        <uses-sdk          android:minSdkVersion="8"          android:targetSdkVersion="18" />        <application          android:allowBackup="true"          android:icon="@drawable/ic_launcher"          android:label="@string/app_name"          android:theme="@style/AppTheme" >          <activity              android:name="com.example.databasetest.MainActivity"              android:label="@string/app_name" >              <intent-filter>                  <action android:name="android.intent.action.MAIN" />                    <category android:name="android.intent.category.LAUNCHER" />              </intent-filter>          </activity>      </application>    </manifest>