Just to clarify -- mainly need exact dates of work history -- 8-20 yrs ago -- don't have info handy --- take forever to find -- have given approximate dates, but not very close-- don't want prospective employers to think lying --- then, started wondering what else they find out about me. Not planning on lying, but don't want to reveal bad if they don't know, or ask about. Nothing criminal, or anything like that. What if what they find out is incorrect? I might not even get an interview because bad info.

There is no database of people's employment history where they will discover exact dates or other details.

Just tell them frankly that you're giving approximate dates for employment that long ago. It is not unusual at all that a normal person cannot recall exact dates of employment from that long ago.

I just include a month and year for previous employment. Employers don't expect you to remember, especially as the time passes.