Setting a specific Redemption Code for Gift Certificates

Is there a way to create specific redemption codes for gift certificates/cards? I don't want to create a coupon code because different rules apply for those (such as including tax and shipping). Plus, the coupon code is redeemed in a different redemption box. I want the customer to redeem the code in the gift certificate box. I am having gift cards printed with a different 10-digit redemption code on each. I tried adding the codes in the phpMyAdmin database by copying an existing gift certificate, but when I tested the redemption code, it did not work. Is there any way to do this?

If I send myself the gift certificate, then Zen Cart generates a random 10-digit code and I don't want that. The cards could not be printed that way.

When creating Gift Certificates you need an entry in the tables:
coupons
coupon_email_track

Perfect! That works. Thanks again, Ajeh! Is there a way to un-redeem the gift cert that I just tested?

I just deleted the entry in coupon_redeem_track and that seemed to work. Thanks!

You should delete from:
coupons
coupon_redeem_track