Draw data flow diagrams for the following situations showing any external agents, processes, data flows and data stores:
1) In order to prepare the payroll for the XYZ Company, the payroll clerk collects all time sheets for the week, checks them to see that they have been correctly filled in, and then looks up each employee's record in turn to find their rate of pay and deductions. She then calculates the gross weekly earnings and the net pay, writing up a pay slip to record all this information. At the end of the process, she places the money in a named envelope along with the pay slip.
2) Airline reservations are performed by reservation clerks who ask the customer the destination and departure date for their trip. The clerk then uses this information to look up the flight file for a flight which is most suitable and has spare seats. The customer chooses the flight and states their preferrred class of seat (eg. economy, first class etc.). The clerk requests the number of seats required which the computer system then updates on the flight master file.
3) Each year the Alumni Association of a university sends subscription renewal notices to all its members which includes their names and addresses as well as their subscription rate. Members who have not paid their subscription one month after the due date are sent a subscription reminder. Before being sent out, subscription renewals and reminders are sorted into postcode order so that a discount on postage can be obtained.
4) A video library lends videotapes to borrowers who must be authorised members. When videos are borrowed and returned, the library staff must place them back on the appropriate shelf for other people to borrow. Late returns are penalised with a fine. The library staff must keep track of fines due and those which have been paid. Videos which are worn or damaged and those which are no longer popular must be taken off the shelves. The library staff must search through catalogues of new releases which arrive in the mail to find videos which might be popular with the library's members. When these new videotapes arrive, they must be put on to holding shelves at the back of the store according to which one of several groups (e.g. children's, drama, comedy) they belong to. The library staff then create an entry for each new videotape in the catalogue database. The number assigned to the videotape in the database includes the copy number of the videotape where multiple copies exist. A sticker with this number is put on the videotape and it is placed on the shelves for borrowing.