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CHAPT E R 2 Introduction to Transaction Processing 65

FI GUR E
2-23 FLOWCHART SHOWING ALL FACTS TRANSLATED INTO VISUAL SYMBOLS

Sales Department Computer Operations Department Warehouse Shipping Department

Customer Edit and Sales A
Order 1
Credit
Credit History
Check
File
Customer
Order Sales
Pick
Goods Order 3
Sales Shipping
Sales Order 2
Log
Input Order Orders
Sales
Order 1
AR File Ship
Goods
Customer Update
Order Program
Update Stock
Inventory Records Sales
Order 2
N Sales Sales
Order 1 Order 3
Stock Records
A
N
Sales
Order 3 Sales
Order 1 Customer
Sales
Order 2
Sales
Order 1

symbol represents each step of the program’s logic, and each symbol represents one or more lines of com-
puter program code. The connector lines between the symbols establish the logical order of execution.
Tracing the flowchart downward from the start symbol, we see that the program performs the following
logical steps in the order listed:
1. The program retrieves a single record from the unedited transaction file and stores it in memory.
2. The first logical test is to see if the program has reached the end-of-file (EOF) condition for the transac-
tion file. Most file structures use a special record or marker to indicate an EOF condition. When EOF is
reached, the edit program will terminate and the next program in the system (in this case, the update
program) will be executed. As long as there is a record in the unedited transaction file, the result of the
EOF test will be ‘‘no’’ and process control is passed to the next logical step in the edit program.
3. Processing involves a series of tests to identify certain clerical and logical errors. Each test, repre-
sented by a decision symbol, evaluates the presence or absence of a condition. For example, an edit
test could be to detect the presence of alphabetic data in a field that should contain only numeric data.
We examine specific edit and validation tests in Chapter 17.