使用Android中的SQLite建立一个数据库，加了一张Book表，增加一个表，升级数据库失败

Question

使用Android中的SQLite建立一个数据库BookStore，加了一张Book表，然后我要增加一个Category表，按照《第一行代码》中的6.4.2所示代码写完后，点击App后直接闪退。（我用的是Andro Studio3.1版本，使用真机开发，系统Androi8.1）。代码如下

主活动代码：
public class MainActivity extends AppCompatActivity {

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);
    Button createDatabase=(Button)findViewById(R.id.create_database);
    createDatabase.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            dbHelper.getWritableDatabase();
        }
    });
}

}

定义一个数据库类MyDatabaseHelper继承SQLiteOpenHelper
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, SQLiteDatabase.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,"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);

}

}

Answer 1

public static final String CREATE_CATEGORY="create table Category("
+"id integer primary key autoincrement,"
+"category_name text,"
+"category_code integer)";

目测缺少2个逗号，是不是有别的问题，你调试下。