John & co. is a Pharmaceutical company which sales lifesaving medicines. You have to draw E-R of sales and purchase system of above company. Main entities of system are Customer, supplier, product, stock etc.
Purposes:
Ensure that you can analyze existing manual system and can draw Entity Relationship Diagrams (ERD) of any proposed system.
Before Starting:
An Entity Relationship Diagram
The entity relationship enables a software engineer to fully to fully specify the data objects that are input and output from a system the attributes that define the properties of these objects, and their relationships
Guidelines to make ERD
The ERD is constructed in an iterative manner. The following approach is taken.
1.During requirement elicitation, customer are asked to list the "things" that the application or business process addresses. These "things" evolve into a list of input and output data objects as well as external entities that produce or consume information.
2. Taking the objects one at a time, the analyst and customer define whether or not a connection exists between the data objects and other objects.
3.Whether a connection exists, the analyst and the customer create one ore more object/relationship pairs.
4. For each object/relationship pair, cardinality and modality are explored.
1. Steps 2 through 4 are continued iteratively until all object/relationships have been defined. It is common to discover omissions as this process continues. New objects and relationships will invariably be added as the number of iterations
grows.
2. The attributes of each entity are defined.
3. An entity relationship diagram is formalized and reviewed.
4. Steps 1 through 7 are repeated until data modeling is complete.
Discussion of the Assignment
Main Analysis Diagrams
Customer Registration Place where new customers are registered Products those are available in this store and register new products Supplier who supply products in this company and also allot them specified regions for their supply
Purchase invoice give three slips on the behalf of suppler that supply products also if return then delete slip from record Sales invoice give three slips on the behalf of order that is placed by customer when return then delete slip from record