relational schema

relational schema
Consider the following relational schema. An employee can work in more than one department; the pct time field of the Works relation shows the percentage of time that a given employee works in a given department.
Emp(eid: integer, ename: string, age: integer, salary: real)
Works(eid: integer, did: integer, pct time: integer)
Dept(did: integer, budget: real, managerid: integer)
Write SQL-92 integrity constraints (domain, key, foreign key, or CHECK constraints; or assertions) or SQL:1999 triggers to ensure each of the following requirements, considered independently.
1. Employees must make a minimum salary of $1,000.
2. Every manager must be also be an employee.
3. The total percentage of all appointments for an employee must be under 100%.
4. A manager must always have a higher salary than any employee that he or she manages.
5. Whenever an employee is given a raise, the manager”s salary must be increased to be at least as much.
6. Whenever an employee is given a raise, the manager”s salary must be increased to be at least as much. Further, whenever an employee is given a raise, the department”s budget must be increased to be greater than the sum of salaries of all employees in the department.
relational schema