android content provider query builder

Question

I have variables, each of them with the possibility of being empty. I use these to create my arguments:

String[] arguments = {argClassOfExercise, argPeriodOfPeriodisation, argAgeGroup, argPrDistanceGroup, argVo2Max};

and to define my WHERE CLAUSE I use

String selection = "catalog.ex_class = ? AND catalog.period = ? AND catalog.age_group = ? AND catalog.pr_comp_grouping = ? AND catalog.vo2max = ?";

putting it all in my cursorloader:

CursorLoader cursorLoader = new CursorLoader(getActivity(), CatalogProvider.CONTENT_URI_TRANSLATION, projection, selection, arguments, null);

Now this will all work fine until one of the variables is empty. Since none of the database values will be equal to and empty string. Is there a possibility to exclude a WHERE CLAUSE if that particular variable is empty?

I know you can write a bunch of IF statements but that would result in me writing 11 of them and I don't think that's really efficient.

Any ideas are welcome

Answer 1

It would be possible to use an SQL expression like (ex_class = ?1 OR ?1 = '') AND ... , but this would be very inefficient.

You should construct the SQL selection string and the arguments array dynamically, and just leave out any entries for emptry strings.