The employee badge number is user-assigned, and serves as an identifier for a particular employee within an organization's structure.
The database ID however, serves as a unique identifier for that particular record on the HRplus database itself. You may have noticed that you are unable to input or change it yourself; its assignment is automatic. This primary identifier is useful for database queries performed by HRplus.
Employee John Doe's employee badge may give him the number E12345 in an organization, but HRPlus will, in addition to that employee badge number, give him a unique database number for its own records, such 000001.
This comes in particularly handy when someone needs to be moved from one company to another in a multi-company setup, where their badge number may change, you have the flexibility to define it as you wish.