java 在android中使用sqlite连接表的最佳方法
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Best way to join tables using sqlite in android
提问by Dale Marshall
I am trying to find out the best way to do a simple table join on my two tables using a sqlite database in an android application. Is the simplest way to use CursorJoiner or is there any easier way?
我正在尝试找出在 android 应用程序中使用 sqlite 数据库对我的两个表进行简单表连接的最佳方法。是使用 CursorJoiner 的最简单方法还是有更简单的方法？
回答by Tim Kryger
In the implementation of SQLiteDatabaseand SQLiteQueryBuilderyou will see that it is possible to pass the tables you want to join to the tableargument of queryeven though the documentation implies it will only take a single name of a table. The documentation for SQLiteQueryBuilderis more clear and even suggests things like foo, baror foo LEFT OUTER JOIN bar ON (foo.id = bar.foo_id).
在SQLiteDatabase和SQLiteQueryBuilder的实现中，您将看到可以将要加入的表传递给table参数，query即使文档暗示它只会采用表的单个名称。SQLiteQueryBuilder的文档更加清晰，甚至建议了诸如foo, bar或 之类的内容foo LEFT OUTER JOIN bar ON (foo.id = bar.foo_id)。
回答by bigsolom
If you're willing to use a third-party library, I recommend using Active Android
如果您愿意使用第三方库，我建议您使用 Active Android
https://github.com/pardom/ActiveAndroid
https://github.com/pardom/ActiveAndroid
using it you can merge tables like this
使用它你可以像这样合并表
From query = new Select()
.from(Foo.class)
.innerJoin(Bar.class)
.on("Foo.Id=Bar.Id");
you can even get a cursor back to use in loaders
你甚至可以让一个游标回到加载器中使用
Cursor cursor = Cache.openDatabase().rawQuery(query.toSql(), query.getArguments());
more details here
更多细节在这里
