AndroidSQLite查询总是空的。-AndroidSQLitequeryisalwaysempty

So right now I'm using this solution in my app Ship an application with a database

现在我在我的应用程序中使用这个解决方案用一个数据库应用程序。

In my main activity, I just want to test to make sure that the database is working, so all I'm doing it a simply query to get some names, all I did was add 3 lines(commented where I added them):

在我的主要活动中，我只是想测试一下，以确保数据库正在运行，所以我所做的只是一个简单的查询来获取一些名字，我所做的只是添加了3行(注释了我添加它们的地方):

       DatabaseHelper myDbHelper;
       SQLiteDatabase myDb = null;

       myDbHelper = new DatabaseHelper(this);
       /*
        * Database must be initialized before it can be used. This will ensure
        * that the database exists and is the current version.
        */
        myDbHelper.initializeDataBase();
        Cursor c;
        String s = null;
        try {
           // A reference to the database can be obtained after initialization.
           myDb = myDbHelper.getWritableDatabase();
//the next 3 lines are all I added
           c = myDb.rawQuery("select name from breads", null);
           s = c.getString(1);
           c.close();
           /*
            * Place code to use database here.
            */
        } catch (Exception ex) {
           ex.printStackTrace();
        } finally {
           try {
               myDbHelper.close();
           } catch (Exception ex) {
               ex.printStackTrace();
           } finally {
               myDb.close();
           }
       }

However, s just remains empty. If I do the exact same query select name from breads in the console, I will get data. Does anyone have any ideas?

然而，s仍然是空的。如果我从控制台的breads中执行相同的查询选择名称，我将获得数据。有人有什么想法吗?

1 个解决方案

myDb = myDbHelper.getWritableDatabase();
//the next 3 lines are all I added
c = myDb.rawQuery("select name from breads", null);
c.moveToFirst(); // ADD THIS
s = c.getString(1);
c.close();