Introduction to The Inventory Management System
Computers are used in almost every field and profession to perform to perform a large number of useful activities. Technological innovation over the last two decided have not only increases the range of technically feasible applications they have also reduced costs so that computer provide a cost effective solution to far wider range of problem than computer provide a cost effective solution to a far wide range of problem than they did before. In business, bank to transfer funds electrically from one location to another use computers. Computers are used to control inventory, and computerized robots are used to wield parts together, paint and much more. With office automation the computer is used for word processing, electronic mail, voice storage and forwarding, facsimile and teleconferencing. In science and engineering, computers are unlocking the secrets of our universe. In business organization, computer easy maintain accounting system and payrole. In health care, computers are used to keep people in shape. In the military computers are used to help people locating oil and diagnosis of medical problem.
Today software is the rapid growing tool for solving complex ideas. In our country most of the business center do not use software. But using software, a shopping mall can maintain its all kinds of daily, monthly, yearly accounts and can produce an invoice.
There is another major area computer application is not so matured as they that is in inventory system. Form the ancient time; inventories are playing a vital role in customer and product information.
Inventory and control system has been designed to aid small-scale business organization for maintaining their day-to-day sales activities. The organization can make it.
Invoice through this software and can produce daily, monthly or yearly reports and a particular any one invoice and also provide hard copy for customer.
GOAL OF THIS PROJECT
The object of the inventory and control system is to maintain sales and monitoring environment. This current work is to design a computerized computer farm’s sales system.
The existing system can handle product’s information, employee’s information and customer’s information. This system managed all sales processing of computer’s farm. By this system customer can easy to handle, easy to get particular employee information, customer information according to employee id and client id. We can find out how many particular products are present in product table and also know if the particular current product is less than ten by the help of alert massage of product form’s quantity field. Also we have a discount option. If we want to discount the total amount then we have a amount then we can entry the amount of discount rate at discrete field and show the amount of the discount at the discount amount field. In order form we have a search option according to invoice, no which can help us to find out. Which date the invoice is created. Every form has necessary button, which can help us new record add, execute query. Clear the form, first record of the database, previous record, next record and last record of the database, of delete the particular form database by the help of alert massage, save the record and exit the form by also help the alert massage. In a word the overall system is user friendly.
FEASIBILITY STUDY AND INVESTIGATION
Although there are again some different of opinion about constitute a database system, the most prevalent view is that such are designed around a signal integrated information file or data link.
This file is located directly accessible on time storage. Transactions are introduced into system only once; all database records that these transactions affect are update at this time of input. The total file may be sub-division into application. The database concept throughout the business. And this requirement, in turn, calls for rigid input discipline; it also measure the some one in the organization must be given the overall authority to standardized that these (and provide any necessary change to) data with company-wide usefulness, such as part number and customer and employee identification codes, in order to ensure that inconsistencies in data not introduced into the system.
One reason for the interest in database system is that a database system, combined with data management software that will organize, process, and present the necessary elements, will enable managers to search, probe and query file contents in order to extract answer to nonrecurring and unplanned question that are not available in regular reports. These question might initially be vague and\or poorly defined, but the manager can browse through the database unit he has needed information. In assemble the needed items from a common database in response to the queries of a manager who is not a programming specialist. In the past manager used to prepare such reports using a database through a programmer at the cost of time and patience.
In addition to having direct access to data generated within the organization, a manager may also have externally produce information at finger trips in the database.
The concept of database:
Informally a database is refereed to a collection of mutually related data, to
the computer hardware that is to store it, and to the programs that are used to store it, and to the programs that are used to manipulate it. In this section, the concept of a file will be defined, since files are the prime component of database concepts.
Then operations or tasks, performed when using a database, will be discussed.
A database is a collection of related data. The data storage for a database is
accomplished by the use of one or more files. A file is defined to be collection of similar records kept on secondary computer storage devices. Typical secondary
storage device us dusk drives with magnetic disks, although a number of alternate possibilities are there. A record is defined to be a collection of related fields containing elemental data items. A data item typically represents a value, which is part of a description of an object or an event. Computational process can manipulate such values.
Computation on a database:
In the foregoing section some of the static aspects of a database are considered, namely, the storage of data as files, records and fields. Now let us look at a database from a dynamic point of view. The study of dynamic behaviors of programming structures is the presswork whenever operating system has to be analyzed. The term computation is used to denote a section of an application that manipulates the database. Most of the computations, which are used to manipulate data collections, are conceptually simple. Four types of computations related to database.
1.Bulding of the data collection:
The updating of a database includes data collection, data organization, and data storage. This aspect is often the most costly part of a database operation.
2.Updating of data elements in the data collection:
The updating of a database includes the additional of new data, change of data values when necessary, and deletion of invalidated or obsolete elements.
3.Retrieval of data from the data collection:
Data retrieval can consists of the fetching of a specific element in order to obtain a stored value or fact, or the collection of related elements to obtain data regarding some collection of sets of related elements to obtain data regarding some relationship, which describes itself when data are joined.
4.Reduction of large quantities of data to useable form:
When the desired information is diffused throughout the database, it may be necessary to access most of its contents and summarize or abstract the data. So that the volume presented is manageable and useable form, statistical summarizes, annual business operating statements, or graphical data presentations are examples have frequently used data-reduction techniques.
Applications are that employ database systems currently include
1.Manufacturing with inventory management, bills-of-materials processing, and production-equipment scheduling.
2.Service industries with lists of capabilities an allocation schedules.
3.Economical models with production and consumption data for allocation planning.
4.Financial institutions with lists of individual accounts, assets, and convertibility of funds.
5.Scientific research with collection of previously gathered data used to determined future research directions.
patient records, database histories, problem classification, and treatment-effectiveness data.
6.Medical services with patient records, database histories, problem classification, and treatment-effectiveness data.
7.Descriptive data on individual and property.
8.Libraries cataloging abstract and index of their holdings.
The evolution of database management system:
Business and business management is one of the major parts of the history of human civilization. Inventory system is one of the major parts of the history of management information systems. Inventories perform their schedule works in a traditional way for more than several hundred years. Today those tools and techniques used in these systems and the prospective has been developed to a new horizon with advanced of time, skill, and experience.
Difficulty with traditional information system
Traditional information systems have often been found wanting because they do not provide information with the desirable properties. More specifically, traditional system often fails in following respects:
1.Information is not timely
Information arrives too late to be of value in planning and decisions.
2.Information is not properly integrated
Potential users may be unaware of the availability of valuable information produced by the internal departments and external sources. The information presented to manager is thus complete as it could be.
3.Information lakes conciseness
Too much detail obscure clarity and prevents managers from focusing attention on those areas of significance that deviate from planned performance.
4.Information is not available in the proper format
Information that arrives is in different format than actually could be of value for better decision making.
5.Information costs too much to produce
This is especially true when then the information is infrequently and at different times. Optimum use has often not been made of personal and available data processing equipment.
6.Information produce is not relevant
Information that produces is of no use because manager is not in a position to take action that will influence the event repotted. To reduce the difficulties with tradition approaches, new computer-oriented management Information System concepts have been developed (and are now emerging).
Management information System:
Management is usually defined as the process of achieving organizational objectives through the effort of other people. Three important points of this definition may be emphasized. The first point is that management is the process, which, when satisfactorily performed, lead to achievement of goals. The second point is that without the establishment of specific objectives, the effective practice of management is most difficult, if not impossible. The third points are that the successful practice of management involves people working together in harmony to achieve desired result. The availability of quantity information is operation the term, Management Information System(MIS) is in dozen of different ways and the definition very in scope and breadth. MIS’s are networks of computer-based data processing procedures Developed in the organization as necessary for the people of the providing manager with and affective information. A procedure is a related group of data processing stapes or methods, which have been established to perform a recurring processing operation.
2.3ABOUT DATABASE MANAGEMENT SYSTEM:
Database management system has evolved from a specialized to central component of a modern computing environment. As such, knowledge about database system has become an essential part of an education in computer science.
A database management system (DBMS) consists of collection of inter related data and a set of programs to access those data. The collection of data, usually referred to as a database, contains information about any particular enterprise.
THE SYSREM DEVELOPMENT LIFE CYCLE
System development life cycle also referred to as a system study. The system analyst gives a system development project meaning and direction. A candidate system is approached after analyst has a through understanding of user need and problems, has developed a viable solution to these problems and then communicates the solution through the boundaries of users in the organization. For example, an inventory and control system may involve users in the sales and order department, the credit department, the warehouse, and the accounting department. To make sure that all users’ needs are met, a project team that represents each user works with the analyst to carry out a system development project. In complex projects, representatives from other user areas influenced by the candidate system as well as information systems specialists may also be included.
To understand a system development, we need to recognize that a candidate system has a life cycle, just like a living system or a new product. System analysis and design are keyed to the system life cycle. The analyst must progress from one stage to another methodically answering key questions and achieving result in each stage.
It is always wise to look ahead, but it is difficult to look further then you can see
Winston Churchill’s remark point out that planning future endeavors, through difficult, is important in operation. System development is not acceptation. Identifying the need for a new information system and lunching an investigation and a feasibility study must be on a MIS muster plane that has management support. Planning cuts across all phases of system life cycle. It is the first step in developing and managing systems.
System analysis is divided into five phases those are follows:
1. System planning and the Initial Investigation,
2. Information Gathering,
3. The Tools Of Structured Analysis.
The tools in structure analysis include the following:
a) Data flow diagram
b) Data dictionary
c) Structured English
d) Decision trees
e) Decision tables.
4. Feasibility Study,
5. Cost/Benefit Analysis.
System design is a solution, a “how to ” approach to the creation of a new system. This important phase is composed of several steps. It provides the understanding and procedural details necessary for implementing the system recommended the feasibility study. Emphasis is on translating the performance requirements into design specifications. Design through logical and physical stages of development.
System design is divided into three phases those are as below:
1. The Process and Stage of System Design
2. Input/Output and Forms Design
3. File Organization and Database Design
No system design is ever perfect. Communication problems, programmers’ negligence, or time constraints create errors that must be eliminated before the system is ready for user acceptance testing. A system is tested for online response, volume of transaction, stress, recovery from failure, and usability. Then comes system testing, which verifies that the whole set of programs hangs together.
System implementation is divided into five phases those are as below:
1. System Testing and Quality Assurance
2. Implementation and Software Maintenances
3. Hardware/Software Selection and the computer Contract
4. Project Scheduling and Software
5. Security, Disaster /Recovery, and Ethics in System Development.
In Visual Basic & MS SQL server, you use database to organize and relate tables and views. Databases provide the architecture for storing your data and have additional benefits as well. When you use a database, you can create table-level extensions such as field and record-level rules, default field values, and triggers. You can also create stored procedures and persistent table relationships. You can use your database to access connections to remote data sources and to create views of local and tables.
This chapter provides guidelines for planning the tables that go into a VB & MS SQL server database. It walks you through the database design of the Imagination traders sample database and provides you with additional sample database designs.
This chapter discusses:
*Using a Database Design Process
*Analyzing Data Requirements
*Grouping Requirements into tables
*Determining the Fields you Need
*Refining The Design
*Sample Database Diagrams
Using a Database Design Process:
If you use an established database design process, you can quickly and effectively create a well-designed database that provides you with convenient access to the information you want. With a solid design, you’ll spend less time constructing the database and you’ll end up with faster, more accurate results.
Note: The terms “database” and ”table” are not synonymous in MS SQL server. The term database refers to a relational database that is a container of information about one or more tables or views.
The key to effective database design lies in understanding exactly what information you want to store and the way a relational database management system, such as MS SQL server, stores data. To efficiently and accurately provide you with information, MS SQL server needs to have the facts about different subjects organization into separate tables. For example, you might have one table that stores fact only about employee and another that stores fact only about sales.
When you organize your data appropriately, you design flexibility you’re your database and gain the capability to combine and present facts in different ways. For example, you can reports that combine facts about employees and facts about sales.
Separating facts into tables adds flexibility to your database.
When you design database, you first break down the information you want to keep as separate subjects, and then you tell MS SQL server how the subjects are related to each other so that MS SQL server can bring the right information in separate tables, you make it easier to organize and maintain your data, as well as to build a high-performance application.
Here are the steps in the database design process. Each step is discussed in later detail in the remaining sections of this chapter.
1.Determine the purpose of your database
knowing the purpose will help you decide which facts you want MS SQL server to store.
2.Determine the tables you need
When you have a clear purpose for your database, you can divided your information into separate subjects, such as “Employees” or “Orders”.
Each subjects will be a table in your database.
3.Determain the fields you need
Decide what information you want to keep in each table. Each category of information in a table is called a fixed and displayed as a column when you brows the table. For example, one field in an Employee table could be emp-name; another could be emp-join-data.4
4.Determain the relationships
Look at each table and decide how the data in one table is related to the data in other tables. Add fields to tables or create new tables to clarify the relationship, as necessary.
5.Refine your design
Analyze your design for errors. Create the tables and a few records of sample data. See if you can get the result you want from your tables. Make adjustments to the design as needed.
Don’t worry if you make mistake or leave things out of your initial design. Think of it as a rough draft that you can refine later. Experiment with sample data and prototypes of your forms and reports. With MS SQL server , it is easy to change the design of your ,database as you are creating it. However, it becomes much more difficult to make change to tables after they are filled with data and after you are built forms and reports. For this reason, make sure that you have a solid design before you proceed too far into building your application.
Analyzing Data Requirements
Your first step in designing aMS SQL server database is to analyze your data requirements by determining the purpose of the database and how it is to be used. This tells you what information you want from the database. From that, you can determine what subject (the fields in the tables).
Talk to the people who will use the database. Brainstorm about the questions you’d like the database to answer. Sketch out the reports you’d like it to produce. Gather the forms you currently use to record your data. You’ll use all this information in the remaining steps of the design process.
Example: Tracking Sales and Inventory
Start by writing down a list of questions the database should be able to answer. How many sales of our featured product did we make month? Where do our best customers live? Who’s the supplier for our best-selling product?
Next, gather all the forms and reports that contain information the database should be able to produce. The company currently uses a printed report to keep track of products being ordered and an order form to take new orders. The following illustration shows these two documents.
Forms and reports show some data requirements for your database.
Imagination Traders also needs to paint mailing tables for customer, employees, and supplies.
After gathering this information, you are ready for next step.
Grouping Requirements into Tables
Determining the tables in your database can be the thickest step in the database design process. That’s because the results you want from your database- the reports you want to point, the forms you want to use, and the questions you want answered—don’t necessary provide clues about the structure of the tables that produce them. They tell you what you want to know but not how to categories the information’s into tables.
See the preceding order form as an example. It includes facts about the customer—the customer’s address and phone number—along with facts about the order. This form provides you with a number of facts that you know you want to store in your database. Although the facts are all on the same form, you can easily prevent common data integrity problems by storing them in separate tables.
Storing information once reduces change of error. For example, if you only use one table to store the information for an order form, suppose that one customer places three different orders. You could add the customer’s address and phone number to your database three times, once for each order. But this multiplies the change of data entry errors.
The customer table stores address information once.
Also, if the customer moves, you’d have to either accept contradictory information or find and change each of that customer’s sales records in the table. It’s much better to create a customer table that stores the customer’s address in your database once. Then, if you need to change the data, you change it only once.
Preventing deletion of valuable information suppose a new customer places an order and then cancels. When you delete the order from the table containing information on both customers and their orders, you would delete the customer’s name and address as well. But you want to keep this new customer in your database so you can send the customer your next catalog. Again, it’s better to put the information about order without deleting customer information.
Look at the information you want to get out of tour database and divide it into fundamental subjects you want to track, such as customers, employees, products you sell, services you provide, and so on. Each of these subjects is a candidate for a separate table.
Tip one strategy for dividing information into look at individual facts and determine what each fact is actually about.
Determining the Fields You Need
To determine the fields in a table, decide what you need to know about the people, things, or events recorded in the table, you can think of fields as attributes, for example, an address field in a customer table contains customers’ addresses. Each record in the table contains customer, and the address field contains the address for that customer.
Here are a few tips for determining your fields:
Relate each field directly to the subject of the table. A field that describes the subject of a different table belongs in that other table. Later, when you define relationships between your tables, you’ll see how you can combine the data from fields in multiple tables. For now, make sure that each field in a table directly describes the subject of the table. If you find yourself repeating the same information in several tables.
Don’t include derived or calculated data
In most cases, you don’t want to store the result of calculations in tables.
Instead, you can have VB &MS SQL server perform the calculations
When you want to see the result. For example, the order form shown earlier in this chapter displays the extended price for each line of the order in the Imagination Traders database.
Include all the information you need it’s easy to overlook important information. Return to the information you gathered in the first step of the design process. Look at your paper forms and reports to make sure all the information you have required in the past is included in your MS SQL server tables or can be derived from them. Think of the questions you will ask VB &MS SQL server. Can VB &MS SQL server find all the answers using the information in your tables? Have you identified fields that will store unique data, such as the customer ID? Which tables include information that you’ll combine into one report or form? For more information on identifying key fields and relating tables, see the sections using Primary Key Fields and Identifying Relationships later in this chapter.
Store information in its smallest logical parts
You might be tempted to have a single field for full names, or for product names, along with product descriptions. If you combine more than one kind of information a field, it’s difficult to retrieve individual facts later. Try to break down information into logical parts; for example, create separate fields for first and last name, or for product name, category, and description.
Report for tracking the inventory of products
The report indicates that the Product table, which contains facts about products sold, need to include fields for the product name, units in stock, and units on order, among others.
Using Primary Key Fields:
The power in a database management system such as MS SQL server comes from its ability to quickly find and together information stored in separate tables. In order for MS SQL server to work most efficiently, each table in your database should include a field or a set of fields that uniquely identifies each individual record stored in the table. This is often a unique identification number, such as an employee ID number or a serial number. In database terminology, this information is called the primary key of the table. MS SQL server uses primary key fields to quickly associate data from multiple tables and bring the data together for you.
If you already have a unique identifier for a table, such as a set of product numbers you’ve developed to identify the items on you can use that identifier as the table’s primary key. But make sure the values in this field will always be different for each record – MS SQL server does not allow duplicate values in a primary key field. For example, don’t u se someone’s name as a primary key, because names aren’t unique. You could easily have two people with the same table.
When choosing primary key fields, keep these points in mind:
· MS SQL server doesn’t allow duplicate or null values in a primary key field. For this reason, you shouldn’t choose a primary key that could contain such values.
· You can use the value in the primary key field to loop up records, so it shouldn’t be too long to remember or type. You might want it to have a certain number of letters or digits, or be within a certain range of values.
· The size of the primary key affects the speed of operations in your database. When you create primary key fields, use the smallest size that will accommodate the values you need to store in the field.
Example: Setting the primary Key for the Products table
The primary key of the Imagination Traders Products table contains product ID number. Because each product number identifies a different product, you don’t want two products with the same number.
The primary key for the product table is the product-id field. In some case, you might want to use two or more fields that together provide the primary key of a table. For example, the product table in the Imagination traders uses two fields as its primary key: product-id. In the next step, you’ll see why.
Now that you’ve divided your information into tables, you need a way to tell MS SQL server & Visual Basic 6.0 how to bring it back together again in meaning full ways. For example, the following form includes information from several tables.
The order Entry form uses information from several tables.
VB is a relational database management system. That means you store related data in separate tables. Then you define relationships between the tables and MS SQL server uses the relationships to find associated information stored in your database.
For example, suppose that you want to phone an employee with questions about a sale the employee made. Employee phone numbers are recorded in the employee table; sales are recorded in the MS-SQL table. When you tell MS-SQL & Visual Basic which sale you are interested in MS-SQL & Visual Basic can look up the phone number based on the relationship between the two tables. It works because Employee-id, the primary key for the employee table, is also a field in the MS-SQL table is called a foreign key, because it refers to a primary key from a different, or foreign, table.
So, to set up a relationship between two tables –Table A and Table B- you add one table’s primary key to the other table. so that it appears in both tables. But how do you decide which table’s primary key to use? To set up the relationship correctly, you must first determine the nature of the relationship. There are three types of relationships between tables:
. One-to-many relationships
. Many-to-many relationships
. One-to-one relationships
Creating a one-to-many relationships:
A one-to-many relationship is the most common type of relationship in a relational database. In a one-to-many relationship, a record in Table A can have more than one matching record in Table B, but a record in Table B has, at mast, one matching record in Table A.
Creating a Many-to-many relationships:
In a many-to-many relationship, a record in table A can have more than one matching record in table B, and a record in table B can have more than one matching record in table A. this type of relationship requires changes in your database design before you can correctly specify the relationship to Visual Basic.
Creating a one-to-one relationships:
In a one-to-one relationship, a record in table A can have no more than one matching record in table B, and a record in table B can have no more than one matching record in table A. this type of relationship is unusual and might call for some changes in your database design.
One-to-one relationships between tables are unusual because in many cases, the information in the two tables can simply be combined into one table.
Refining the design:
When you have the tables, fields, and relationships you need, it’s time to study the design and detect any flaws that might remain.
You might encounter several pitfalls while you are designing your database. These common problems can cause your data to be harder to use and maintain:
. Do you have field with a large number of fields that don’t all relate to the same subject? For example, one table might contain fields pertaining to your customers as well as fields that contain sales information. Try to make sure each table contains data about only one subject.
. Do you have fields that are intentionally left blank in many records because they aren’t applicable to those records? This usually means that the fields belong in another table.
. Do you have a large number of tables, many of which contain the same fields? For example, you have separate tables for January sales and February sales, or for local customers and remote customers, in which you store the same type of information. Try consolidating all the information pertaining to a single subject in one table. You might also need to add an extra field, for example, to identify the sales date.
Create your tables, specify relationships between the tables, and enter a few records of data in each table, see if you can se the database to get the answers you want. Create rough drafts of your forms and reports and see if they show the data you expect. Look for unnecessary duplications of data and eliminate them.
As you try out your initial database, you will probably discover room for improvement. Here are a few things to check for :
. Did you forget any fields? Is there information that you need that isn’t included? If so, does it belong in the existing tables? If it’s information about something else, you might need to create another table.
. Did you choose a good primary key for each table? If you use it to search for specific records, is it easy to remember and type? Make sure that you won’t need to enter a value in a primary key field that duplicates another value in the field.
. Are you repeatedly entering duplicate information in one of your tables? If so, you probably need to divide the table into two tables with a one-to-many relationship.
. Do you have tables with many fields, a limited number of records, and many empty fields in individual records? If so, think about redesigning the table so it has fewer fields and more records.
As you identify the changes you want to make, you can alter your tables and fields to reflect the improved design. For information about modifying tables, working with tables.
Refining the products table:
Each product in the Tasmanian Traders stock falls under a general category, such as Beverages, Condiments, or Seafood. The Products table could include a field that shows the category of each product.
Suppose that in examining and refining the database, Imagination Traders decides to store a description of the category along with its name. If you add a Category Description field to the Products table, you have to repeat each category description for each product that falls under the category – not a good solution.
A better solution is to make Category a mew subject for the database to track, with its own table and its own primary key. Then you can add the primary key from the Category table to the Products table as a foreign key.
The Category table provides a place to store category information efficiently.
The Category and products tables have a one-to-many relationship: one category can have more than one product in it, but any individual product can belong to only one category.
Sample Database Diagrams:
The database diagrams in this section might give you ideas for designing your own database. These databases aren’t included with Visual Basic; they’re included here as examples of the types of databases and tables you can create.
This database structure stores appointments for a professional office, and could easily be modified for use in an office of doctors, dentists, lawyers, or accountants. The appointments table has a multiple-field primary key to uniquely identify each appointment. This primary key, the “client_sta” index, is created by indexing in an expression that combines the client_id and date_start time fields.
This database structure stores human resources information. The Job History table stores information on each hire or promotion, so it can contain many records for each employee.
Before designing a system, it should have clear conception about the design face for achieving this goal.
A person should have the knowledge about system planning and design. For designing an ideal and effective system we should flow the step, which is depicted by the following figure.
To develop our software we have collect many information from various organizations there are Arrange, one-step mall, pride and stop & shop. We have divided the information resource into two phases one is the interview and other is the question.
The interview: Interviewing is the most significant and productive fact finding technique available to the system analyst. Interview is a face to face interpersonal role situation in which a person called the interviewer asks a person being interviewed questions designed to gather information about problem areas.
Here may e creating an opportunity for flexibility in eliciting information because the person (interviewer) and the person in interviewed meet face to face.
The questionnaire: The questionnaire is another tool, which can be used at various times by the system analyst in the system development process. When the analyst decides to make use of questionnaire there are a few, but important guidelines to follows:
1. Explain the purpose, use, security and disposition of the responses.
2. Provide detaile4d instructions on how you want the questions competed.
3. Give a time limited or a deadline for return of the questionnaire.
4. It is economical and requires less skill to administer than interview.
5. The questionnaire places less pressure on subjects for intermediate responses.
6. Identify each questionnaire by respondent’s name, job title, department etc.
7. Include a section where respondents can state their opinions and criticisms.
The Inventory Problem:
The inventory problem is one of the most typical semi-additive measure problems. The inventory represents a whole class of semi-additive measure problems that share a common attribute: keeping track of data snapshots. Snapshots are typical in applications in which balances are involved, such as account balances, stock tickers, head count tracking, contact management, and active insurance policies management. Data snapshots (as opposed to pure transactions) disable the ability to aggregate data over time correctly. Although this article refers to the inventory problem, remember that the applicability of the proposed techniques is broad and can be adapted without change to wide variety of business problems.
The inventory cube has this structure:
- Products: All Products, Family, Category, Name.
- Computer Firm: All, Computes.
- Time: Year, Quarter, Month, Week.
- Quantity (SUM)
- Value (SUM)
As explained earlier, summing the quantities and values over the time dimension yields incorrect results. These are the items that must be analyzed:
. The average quantities and stock values in each time period.
. The opening and closing balances for each time period.
. The change in inventory levels between consecutive periods and.parallel periods.
. The minimum and maximum inventory levels in a time period.
. The relative contribution of the stocked item to the overall stock value.
End users should not see any data generated by summing over the time dimension.
CHAPTER FOUR TABLE DESIGNING
Table Name : Category
Table Name: User
Table Name: Department
Table Name: Wise Product
Table Name: Payment
Table Name: Supplier
Table Name: Measurement Unit
Table Name: Product
Table Name: Purchase Master
Table Name: Purchase
Table Name: Request Detail
Table Name : Request Master
Programming in Visual Basic
In Visual Basic, we use variables to temporarily store values during the execution of an application. A variable can be thought of as a placeholder in memory for an unknown value.
For example, imagine we are creating a program to track the sales of PCs. We do not know the price of a PC or the quantity socked until the sale actually occurs.
We can use two variables to hold the unknown values that is, PCPrice and PCSold. Each time the program is run, the user supplies the values for the two variables. To calculate the total sales and display it in a Textbox named txtSales, our code would be :
TxtSales. Txt = PCPrice * PCSold
The expression returns a different total each time, depending on what values the user provides. Variables allow us to make a calculation without having to know in advance what the actual inputs are.
Variable names in Visual Basic can be up to 255 characters long and provided the first character is a letter followed by any number of letters numbers and underscores. The following list shows some variable names and indicates whether they are valid or not:
Ø Area 1_square Acceptable
Ø 1Area_square` Not acceptable First
character is not a letter
Ø Area.1 Not acceptable uses a
Ø Area&1 Not acceptable uses &
inside the name
Ø Area Rectangle Square Acceptable 19
Understanding Access- Visual Basic as a Client/Server Combination
Visual Basic is the most commonly used visual programming environment. It allows us to create front-end applications.
Microsoft Access is an RDBMS used to create client/server applications for small to medium size enterprises. It is used most popularly with Visual Basic as the front-end.
Data access in Visual Basic gives us tools to create and use structured database systems to manage our application’s data. One of these tools is the data control.
The ability to create and access a database such as Microsoft Access gives us many programming advantages:
> It lets us write programs that use existing databases.
> It allows our application to share data with other programs.
> It simplifies our programming, since we do not need to handle low-level file accessing and searching.
Data access in Visual Basic consists of performing operation on a physical database. We can display the results of these operations and accept input from to user on Visual Basic forms, using controls.
This approach simplifies the code we need to write and insulates us from the underlying structure and mechanics of retrieving and updating data.
Advantage of Visual Programming:
>Visual development of graphical user interfaces which are easy to use and easy to learn.
>A programmer need not write code to display the required component.
>For example, the visual programming environment displays a list of available components. The programmer picks up the required component from this list to display it.
>The component can be moved, resized and even deleted, if so required.
>There is no restriction on the number of controls that can be placed on a from.
>The programmer can create the user interface visually, he can align move or size the components as required without
having to resort to writing code.
> The interface components provided by the visual programming environment have some code built into them.
> For example, a button ‘knows’ when it has been clicked upon. In the case of conventional programming tools, the programmer has to write code to determine the component that has been clicked and then execute the appropriate code.
Data type names
Variables are placeholders used to store values; they have names and data types. The data type of a variable determines how the bits representing those values are stored in the computer’s memory. When a variable is declared, we can also assign a data type for it. All variables have a data type that determines what kind of data they can store.
By default, if we don’t assign a data type, the variable is given the Variant data type.
If we assign a data type to a variable, Visual Basic can handle that data more efficiently. For example, a variable to store a person’s age is best represented as a numeric data type.
The following is the list of data types supported by Visual Basic.
> Numeric data types
à Long Integer
> Byte data type
> String data type
> Boolean data type
> Date data type
> Object data type
> Variant data type
> User-defined data type
To declare a variable is to tell the program about it in advance. We declare a variable with the Dim statement, supplying a name for the variable:
Dim variable name ( As type)
The Dim statement is the short form of dimension.
The optional ( As type) clause in the Dim statement allows us to define the data type of the variable we are declaring. Data types of information the variable stores.
For example, to declare a variable num1 as an integer the declaration in Visual basic would be as follows:
Dim numl As Integer
Some points about Global and Local Variables:
> Memory for the variables is allocated when the declaration for the variable is encountered.
> Global variables are declared just before the code for the program starts. Thus, memory for global variables is allocated just before the execution of the program begins. This memory stays allocated till the program terminates.
> Memory for the local variables is allocated at the start of the procedure when the declarations are encountered and the memory is freed when the end of the procedure is reached.
> It is better to use local variables than global variables because memory is used only as and when required by the local variables.
Key Concept: Key is a minimal set of attribute or attributes that identify a now which distinguish entities from each other. Key must be needed to easy access database:
(a) To for relation among altitudes in a relation or a group of relation.
(b) To identify a tuple uniquely.
Function of Key:
(1) Super Key
(2) Candidate Key
(3) Primary Key
(4) Foreign Key
Super Key: The combination of the attributes able to select specific row in the relation uniquely is called a super key.
Candidate Key: A candidate key is that attribute in the relation which must be able to select a row or record uniquely without help of other. To do 00 candidate key must satisfy two conditions
(1) The value of that attribute can never be of null.
(2) That attribute never accepted duplicate value.
Primary Key: An attribute able to select a row in the relation uniquely and nominated by the DBA as key of that relation is primary key.
Foreign Key: The primary key of a relation exist is other relation to represent its parent tubule is called a foreign key.
Simple applications can consist of just a single form, and all of the code in the application resides in that form module. As the applications and more sophisticated, we may need additional forms and there are chances that certain code gets repeated in several forms.
To avoid such duplication of the code, we create a separate module containing a procedure that implements the common code. Visual Basic provides three modules:
From modules: -Associated with each form is a related form module, which contains its code. For each control placed on the form the form module contains a corresponding set of procedures, which are executed in response to an event. From modules have a filename extension (.FRM).
Standard modules: Code that is not related to a specific form or control is placed in a different type of module, called the standard module (.BAS). Procedures that are to be used repeatedly in response to events in several different controls are placed in the standard module. This avoids duplication of the code.
Class modules:- A class module (.CLS) is used to create controls that can be called from procedures within the application, A standard module contains only code whereas, a class module contains both code and data that is, we can think of it as a control without a physical representation.
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1. Fundamentals of Database System by Elmasri & Navathe.
2. UML Crash Course by Thomas A Pender.
3. Software Engineering by Roger S. Pressman.
4. Sql, Pl/Sql by Ivan Bayross.
5. Teach yourself Visual Basic in 21 Days – Sams.
6. Visual Basic 6.0 by Gary Cornell