Re: DBDesign Q2:

The following seems to match your business rules. Treat Department Manager as an attribute of the Department rather than the Employee.

CREATE SCHEMA AUTHORIZATION dbo

CREATE TABLE Employees (empno INTEGER PRIMARY KEY, deptno INTEGER NOT NULL REFERENCES Departments (deptno), UNIQUE (deptno, empno))

CREATE TABLE Departments (deptno INTEGER PRIMARY KEY, deptname VARCHAR(20) NOT NULL UNIQUE, deptmanager_empno INTEGER NOT NULL, FOREIGN KEY (deptno, deptmanager_empno) REFERENCES Employees (deptno, empno))

The usual caveat about design questions applies: it's very difficult to give design advice online without the opportunity to research a particular situation in detail.

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David Portas