per diem
by the day

By day they could take pretty good care of themselves.

One is a young man, 23 years old and a business student by day.

In summer quite the other way, I have to go to bed by day.

By day, he works in technology support for a local university.

I never could have enough of her, by day or night.

By the next day both she and her child had died.

I should have something for you by the following day.

By the following day, he was back to full health.

By the next day we were ready to go to work.

They would be ready to leave by the next day.