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; /**  * 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.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;     @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",null,2);         btn.setOnClickListener(new View.OnClickListener() {
              @Override             public void onClick(View v) {
                  dbHelper.getWritableDatabase();             }         });     } }