CREATE TABLE CEOShareholding (
	-- CEO Shareholding involves CEO and CEO is a kind of Manager and Manager is a kind of Employee and Employee works for Company and Company has CompanyName,
	CEOCompanyName                          varchar NOT NULL,
	-- CEO Shareholding involves CEO and CEO is a kind of Manager and Manager is a kind of Employee and Employee has EmployeeNr,
	CEOEmployeeNr                           int NOT NULL,
	-- CEO Shareholding involves Company and Company has CompanyName,
	CompanyName                             varchar NOT NULL,
	PRIMARY KEY(CEOCompanyName, CEOEmployeeNr, CompanyName)
)
GO

CREATE TABLE Company (
	-- Company is run by CEO and CEO is a kind of Manager and Manager is a kind of Employee and Employee works for Company and Company has CompanyName,
	CEOCompanyName                          varchar NOT NULL,
	-- Company is run by CEO and CEO is a kind of Manager and Manager is a kind of Employee and Employee has EmployeeNr,
	CEOEmployeeNr                           int NOT NULL,
	-- Company has CompanyName,
	CompanyName                             varchar NOT NULL,
	PRIMARY KEY(CompanyName)
)
GO

CREATE TABLE Employee (
	-- Employee works for Company and Company has CompanyName,
	CompanyName                             varchar NOT NULL,
	-- Employee has EmployeeNr,
	EmployeeNr                              int NOT NULL,
	-- maybe Employee reports to Manager and Manager is a kind of Employee and Employee works for Company and Company has CompanyName,
	ManagerCompanyName                      varchar NULL,
	-- maybe Employee reports to Manager and Manager is a kind of Employee and Employee has EmployeeNr,
	ManagerEmployeeNr                       int NULL,
	PRIMARY KEY(CompanyName, EmployeeNr),
	FOREIGN KEY (CompanyName) REFERENCES Company (CompanyName),
	FOREIGN KEY (ManagerCompanyName, ManagerEmployeeNr) REFERENCES Employee (CompanyName, EmployeeNr)
)
GO

ALTER TABLE CEOShareholding
	ADD FOREIGN KEY (CompanyName) REFERENCES Company (CompanyName)
GO

ALTER TABLE CEOShareholding
	ADD FOREIGN KEY (CEOCompanyName, CEOEmployeeNr) REFERENCES Employee (CompanyName, EmployeeNr)
GO

ALTER TABLE Company
	ADD FOREIGN KEY (CEOCompanyName, CEOEmployeeNr) REFERENCES Employee (CompanyName, EmployeeNr)
GO