auto-enter serial with letters: problem as a 'key'?
Hi all, I'm working with a database with 20+ tables and need to figure out what to do for keys for each table. I've never had formal training in making databases and only learned recently that I should *never* use a edit-able field as a key (because links can be broken when the value is changed, etc.; I know, common knowledge, right?). This leads me to consider what values I can use as each table's 'key.' I had already used a auto-enter serial number that included two sets of letters along with the incrementing number (e.g., TCI309L), which included my firm's initials and a terminal letter which indicates the type of data (L=Livestock, M=Manure, F=Farm field, etc.). But, I have several questions related to this situation:
1. Should I have a unique, auto-enter serial key Field for each unique table in the database?
2. Am I violating the FM laws of nature by mixing alphanumerics for the auto-enter serial (NB: each Field is identified as a Text field).
Any thoughts/recommendations/condemnations welcome.