Good day,
I must first commend you on the wonderful work you have done with the database models you have provided.
I seek your assistance with the following :
A construction company has about 200 employees. The company is organized into several departments and every 
employee should belong to a department. 
The employees are classified as managers, junior managers and workers. 
A manager is responsible for one construction project and supervises several junior managers and workers. 
In a construction project, each junior manager has his or her own major specialty area such as electrical, civil engineering etc. 
Each worker has a specialty such as painting, masonry, carpentry, administration , driving etc.. 
An employee may or may not have a degree and may be married or single. 
An employee has a name, address and telephone number. 
Each employee is paid a monthly salary.
The company has several construction sites and a main office that monitors and oversees all the construction sites. 
An employee can work either on a construction site or in the main office. 
Each project has only one manager and has start and end dates. 
The project belongs to only one client and the construction cost is decided between the company and the client. 
An employee may be asked to work on more than one projects at the same time, depending on the resource needs of the project. 
The system should keep track of when the employee begins to work on a project and when he/she stops working on a project.
In a project, a given part or material can be supplied by more than one supplier. 
Suppliers can supply parts to different projects. 
A supplier may produce the parts/material it supplies or may buy the parts from manufacturers. 
Each construction site stores the parts/material it is supplied until they are used.

Thank you in advance
Best Regards,
Garth