I am trying to determine how the tables need to be linked in which ways.

The employees tables is directly linked to a number of tables which provide more information. A few of those tables have even more details. 

* Employees have a unique **employeeid** but I understand best practice is to still have a id?
* Customers have a unique **customerid**
* Employees have a manager
* Managers are employees
* Customers have a manager associated with them. manager associated with them
* Employees may have a academic, certification and/or professional information.

With all of this said what would be the best recommendation for creating primary and foreign keys? Is there a better way to handle the design?

![Version2](https://i.stack.imgur.com/iG4OW.png)

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**EDIT**

Updated diagram to reflect feedback thus far. See comments to understand changes taking place.

![v3schema](https://i.stack.imgur.com/iefIz.png)