GROUP BY with CursorLoader

Question

How do I define a GROUP BY query for my CursorLoader?

The two constructors for a CursorLoader I see take either a single Context or a Context, Uri, projection, selection, selectionArgs and sortOrder.

But no groupBy.

(I'm using the support package for a Android 2.3 device)

Answer 1

Not really...

You can define a specific URI to your specific GROUP BY clause.

For example, if you have a table mPersonTable, possibly grouped by gender, you can define the following URIs:

PERSON
PERSON/#
PERSON/GENDER

When querying, switch between your queries so you can add your group by parameter:

public Cursor query(Uri uri, String[] projection, String selection,
            String[] selectionArgs, String sortOrder) {
   String groupBy = null;
   switch (mUriMatcher.match(uri)) {
      case PERSON_ID:
         ...
         break;
      case PERSON_GENDER:
         groupBy = GENDER_COLUMN;
      case PERSON:
        SQLiteQueryBuilder builder = new SQLiteQueryBuilder();
        builder.setTables(mPersonTable);
        builder.setProjectionMap(mProjectionMap);
        return builder.query(db, projection, selection, selectionArgs, groupBy, having, sortOrder, limit);
      default:
         break;
   }
}

In fact, you could pass any sort of parameters to your query

Obs.: Use a UriMatcher to match the uri with your query implementation.