An ID number can be automatically generated for each database record upon their submission.
To enable this feature, go to your Database and select Edit Form Template.
Once in the form builder, add the field type named Sequence.
You can configure the prefix, suffix, and the minimum numbers to display (e.g. 3 will always display records as 001, 002, etc).
If you have existing records you would like to generate an ID for, Edit and Save each of them or use the Export / Import function to do it in bulk.