java – Best way to join tables using sqlite in android-ThrowExceptions

Exception or error:

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?

How to solve:

In the implementation of SQLiteDatabase and SQLiteQueryBuilder you will see that it is possible to pass the tables you want to join to the table argument of query even though the documentation implies it will only take a single name of a table. The documentation for SQLiteQueryBuilder is more clear and even suggests things like foo, bar or foo LEFT OUTER JOIN bar ON (foo.id = bar.foo_id).

###

If you’re willing to use a third-party library, I recommend using Active Android

https://github.com/pardom/ActiveAndroid

using it you can merge tables like this

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

Cursor cursor = Cache.openDatabase().rawQuery(query.toSql(), query.getArguments());

more details here

Leave a Reply

Your email address will not be published. Required fields are marked *