I'd like the employee ID to auto increment and populate automatically whenever a new employee is being added to the record.
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If your initial DB table and CDT are set up correctly to handle this, then it should work automatically. If it's an existing one and it doesn't seem to be working, then you'll need to share some more details with us - like if the DB primary key column is set to "auto increment", if the CDT is configured to match that, etc. If you're using Record Type data instead of CDT/DB, that might change some things too so you'll need to specify in that case as well.