Sad Chapter 2 and 3

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CHAPTER II
SYSTEM ANALYSIS

2.1 Data Flow Diagram
It is the pictorial representation of the logical inter-relationship between the data and the process. It can be define as pictorial representation of logical inter-relationship between the procedures, input, output and their data stores. It also shows the flow of data from external entities into the system, showed how the data moved from one process to another, as well as its logical storage. . There are only four symbols: 1. Squares representing external entities, which are sources or destinations of data. 2. Rounded rectangles representing processes, which take data as input, do something to it, and output it. 3. Arrows representing the data flows, which can either be electronic data or physical items. 4. Open-ended rectangles representing data stores, including electronic stores such as databases or XML files and physical stores such as or filing cabinets or stacks of paper. Creating a data flow diagram is a process driven task. Consequently, it is relatively easy to overlook key data elements and composites. Balancing a data flow diagram verifies the model’s internal consistency, but does not necessarily reveal missing elements. Attempting to balance a significant logical model without appropriate software (such as CASE software) is at best difficult and can be misleading. Beginners and users often confuse data flow diagrams with process flowcharts.

Sales
Item order
Item order
Items Sold
MANAGER
Physical inventory
Stock number Stock on hand
Identify
sale items
Stock number Stock on hand
Stock number Stock on hand
Inventory
Stock number quantity sold

Process shipment
Stock number Description Selling price
Stock number Stock on hand Reorder quantity
SUPPLIER
Order
Stock number Quantity received
SUPPLIER
Update Inventory
Reorder Stock
Invoice
CUSTOMER
Sell Merchandise
Order
Sales data
Invoice
Invoice
Item sold
Item sold
Item sold
Item sold
Items Sold
FINANCIAL
Report cash flow
Data Flow Diagram
Cash flow Cash flow

Reorder

Item order

2.1.1 Context Diagram
POS/
INVENTORY
SYSTEM
CUSTOMER
SUPPLIER
MANAGER
FINANCIAL

Computerize
Invoice

Purchase Replacement
Cash Flow

Overstock Sale Item Shortage Reorder Reorder Shipment

2.1.2 Exploded DFD

SUPPLIER

Analyze
sales data
MANAGER
Analyze inventory data
Items Sold

Reorder data

Inventory

SUPPLIER
Make order decision
Compute expected sales
Generate order
Item Order

MANAGER
Vendor

Date of sale
Invoice number Stock number Quantity
Sales/day
Stock on hand Reorder point
Stock on hand Reorder point
Sales/day
Expected sales Reorder point Stock on hand
Stock number Supplier code
Expected sales
Description Reorder Quantity

Reorder data
Order
Supplier name Supplier address
Supplier code Reorder time Supplier price

Sales

2.2 System Flowchart
Sell
Products...
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