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Computer Science 255


Third Hour Exam




Name ______________________

















Tuesday, Dec. 3
100 pts.



Please Read All Questions Before Starting the Exam

1.	(20 pts.)	The file PARTS-FILE contains records as 
follows:
			01	PARTS-REC.
				02	PNO			PIC X(5).
				02	PNAME		PIC X(20).
				02	INVENTORY	PIC 9(5).

	The file MODIFY-FILE contains records as follows:

			01	BASIC-REC.
				02	PNO			PIC X(5).
				02	TRANSACTION	PIC X.
					88	ADD-TO-INVENTORY
						VALUE "A".
					88	SUB-FROM-INVENTORY
						VALUE "S".
			01	ADD-REC.
				02	FILLER		PIC X(6).
				02	ADD-AMT		PIC 999.
			01	SUB-REC.
				02	FILLER		PIC X(6).
				02	SUB-AMT		PIC 999.

	If the record in MODIFY-FILE is an ADD-REC, then the amt 
is to be added to the inventory amount of the 
corresponding record; if a SUB-REC, the amount is to be 
subtracted.  Both files are in ascending order by part 
number.

	On the following page, write the code necessary 
(procedure division only) to perform the indicated 
operations on the incoming master file, producing a new 
master file.  Display an error message if a transaction is 
attempted on a nonexistent record, or if a subtract 
operation brings an inventory level below zero.  For this 
exercise, do not consider any other errors (such as 
sequence error or inventory above a maximum amount).

Working space for problem 1


2.	(15 pts.)	List the five basic steps in the software life 
cycle model with a brief explanation of each.




















3.	(10 pts.)	Briefly define:

	a.	Entity integrity







	b.	Referential integrity


4.	A series of questions leading up to some more COBOL code.

	In the following, assume that a company has a number of 
geographical regions in which it works (eg., NorthWest region, 
NewEngland region, etc.)  Each region has a region number 
(PIC X(5)), a region name (PIC X(20)), and the name of a city in 
which the headquarters for that region are to be found (PIC 
X(20)).  The company also has salespeople.  Each salesperson 
has an employee number (PIC X(9)), and a name (PIC X(20), 
not necessarily unique).  Each region has a number of 
salespeople, but each salesperson is assigned to one (and only 
one) region.

a.	(15 pts.)	Model this situation using an entity-relationship 
diagram.

b.	(20 pts.)	Write SELECT statements for the files derived from 
the entity-relationship diagram.  Use the region number for 
the primary key for regions, but build a unique key over the 
region name.  Briefly justify any other indexes (but be sure to 
include any that would probably be useful).

c.	(20 pts.)	Write the code necessary to write out the employee 
name and region name and number of employee number 
"123456789".