How can I simplify this query?
I've managed to simplify it a bit:

SELECT sum(amount) / (julianday('now', '+1 day') - julianday('2012-08-11')) * 14 AS 'Cost Per Fortnight'
FROM
(
    SELECT transdate, transamount AS amount, CategID, SubCategID
    FROM checkingaccount_v1 AS "transaction"

    UNION ALL

    SELECT transdate, splittransamount AS amount, splittransaction.CategID, splittransaction.SubCategID
    FROM splittransactions_v1 AS splittransaction
    JOIN checkingaccount_v1 AS "transaction" USING (TransID)
)
JOIN Category_v1 AS category USING (CategID)
JOIN SubCategory_V1 AS subcategory USING (SubCategID)
WHERE transdate BETWEEN date('2012-08-11') AND date('now')
    AND categname = 'Food'
    AND subcategname = 'Groceries'