I have a SQL head-scratcher:
SELECT invoice_id, customer_name, invoice_date, item, unit_price, qty
FROM invoices a, invoice_lines b, customers c
AND a.invoice_date between ? and ?
The query runs well most of the times, but occasionally produces blank output.
Assuming there are always records that satisfy the matching criteria, does anyone have any ideas on why the above would result in blanks? Anything quirky about the way I wrote the sql code that Filemaker doesn't like?
Some of the fields are indexed for performant reasons, but I don't think that is why I would have this problem.