# Not every payload has a currency field (only some purchases do)

Canonical URL: <https://datadriven.io/problems/not-every-payload-has-a-currency-field-only-some-purchases-133d8d8a>

Domain: SQL · Difficulty: medium

## Problem

Not every payload has a currency field (only some purchases do). Return event_id and currency for events whose payload actually contains a currency value (skip the NULLs), ordered by event_id.

## Related

- [All practice problems](https://datadriven.io/problems)
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