Re: Resiliency To New Data Requirements

After implementing the prior solutions, we find out that emp#s are not unique because Sam's emp# is also 123, works in marketing dept, has salary 10,000.

RMDB: (schema change, update existing data) In table employee, add field empID (autoID). In table employee_dept, change emp# field to empID and update data.

Add data for Sam.
INSERT employee (123, sam, 10000);
INSERT employee_dept (4, marketing);

Update query to find Mary via table join on IDs. SELECT employee.*
FROM employee INNER JOIN employee_dept ON employee.empID = employee_dept.empID
WHERE ((employee_dept.dept)="safety") AND ((employee.salary)=20000);

DBD: (no changes, add new data)
(new 'sam 'employee)
(create sam emp# 123)
(create sam dept (val+ 'marketing))
(create sam salary 10000)

(; Original query still ok, returns Mary)
(and (select employee instance *) (select * dept safety) (select *
salary 20000)) Received on Wed Aug 02 2006 - 22:51:02 CEST