Inventory management system is a typical information management system (m is), and its development mainly includes the establishment and maintenance of background database and the development of front-end application programs. For the former, it is required to establish a database with strong data consistency and integrity and good data security. For the latter, the application is required to be fully functional and easy to use.
After analyzing this situation, we use Microsoft's VisualBasic development tools, and use all kinds of object-oriented development tools provided by it, especially ADO, which is an intelligent object, to manipulate the database conveniently and concisely, and we can develop a feasible and satisfying system in a short time.
Keywords: inventory management ADO object inventory ABC analysis
The first chapter is an overview.
1. 1 the necessity of inventory management
Most inventory management theories believe that inventory is the sum of all tangible and intangible materials in physical and logical warehouses, including finished products, raw materials, work in process, goods in transit, pre-production materials and spare parts. Although it is necessary to hold some inventory, too much inventory is not only useless but also takes up funds. The occupied funds are very necessary for the company's development and new product development; Reducing capital occupation can also greatly reduce the interest and risk of bank loans. It is more effective to strengthen inventory management for the material inventory with particularly large purchase volume and large fluctuation in the market price of purchased parts. Therefore, it is very important to balance the company's inventory investment and other capital needs.
1.2 inventory classification
How to manage inventory is the biggest difficulty and challenge of inventory management. Therefore, it is necessary to establish a planning and control system through MRPII material master planning module and procurement module to effectively implement inventory management and procurement compensation. Through investigation, we know that any inventory can be divided into the following three categories:
Class A commodities: high value-relatively few commodities, whose value accounts for 70-80% of the total inventory value. Usually 15-20% items.
Category B goods: median-total value accounts for 15-20% of total inventory value. The number of items is in the middle, usually accounting for 30-40% of the number of items.
Class C commodities: low value-the total inventory value is almost negligible, accounting for only 5- 10%. Most projects, usually accounting for 60-70%.
Obviously, Class A items are the key; If we focus on Class A items, reducing their inventory by 10-50% will be a considerable reduction in the total inventory.
There are several basic rules about ABC classification:
A. degree of control:
Strictly control Class A goods, including complete and accurate records, high-level supervision and regular review, frequent delivery by suppliers according to large contract orders, and close tracking of workshops to reduce lead time.
Normal control of Class B goods, including good records and daily attention.
Use as simple and convenient control as possible for Class C items, such as regular visual inspection of physical inventory, brief record or simple marking method to indicate that supplementary inventory has been ordered, large inventory and order quantity are adopted to avoid shortage, and low priority is given when arranging workshop schedule.
B. priority
Give priority to Class A projects in all activities to reduce their lead time and inventory.
Class B items should be handled normally and given high priority only when they are critical.
Give the lowest priority to class C items.
C. Ordering process
Provide timely and accurate procurement information and status query for Class A projects. Computer data need to be checked manually, counted by stages, and checked frequently to reduce inventory.
For class B goods, in a certain period or when there are major changes, the inventory data and order points are reviewed, and MRPII operations are handled as usual.
Class C materials can be counted or calculated according to the ordering point. MRPII usually does not plan orders. It can be controlled by the experience of business people.
From the above we can see the importance of inventory management. Therefore, inventory management is an important part of enterprise management. The market needs inventory goods to provide users, and the operation of enterprises needs inventory to ensure the supply of various drugs for drug sales. Inventory has an extremely important impact on the improvement of production efficiency. Therefore, inventory management system is the center of computer management system. Because, the business activities of all enterprises are inseparable from the activities of logistics.
1.3 inventory management objectives
The main goal of inventory management is to ensure the smooth logistics in enterprise production through the management and control of all warehousing activities and the effective statistics and analysis of inventory data, so that decision makers can find problems as soon as possible, take corresponding measures, adjust inventory structure, shorten reserve cycle, speed up capital turnover and minimize inventory occupation. At the same time, through regular warehouse inventory, the loopholes in management can be made up in time. Make the inventory management system reflect the current situation of each warehouse in the enterprise in real time, and provide all kinds of managers with the information they need from different aspects, so as to coordinate the operation of the enterprise and receive greater benefits. Inventory management system is the basis of coordinating the production and operation of enterprises, and the accurate, convenient and effective analysis of its data is the key to the smooth operation of the whole computer management system.
Chapter II Development Background
The inventory management of enterprises is often very complicated. Due to the variety of materials, different ordering, management and distribution channels, different management systems among enterprises and various statistical reports, a set of inventory management information system must be compiled for warehouse inventory management to realize computerized operation, and corresponding schemes must be formulated according to the specific conditions of enterprises.
According to the current enterprise management system, the general inventory management system is always divided into several departments to plan, order, write off, collect, count and put into storage according to the material category, send materials and equipment according to the needs of various departments of the enterprise, and make inventory and bookkeeping at any time and on schedule according to the needs of enterprise leaders and their own management, and make statistical analysis on a monthly, quarterly and annual basis, and generate corresponding reports. In order to strengthen the management of key materials and equipment, we must know their reserves and consumption regularly, and carry out quota management according to the comparison between plan fixed and the actual quota, so as to make the use of funds reasonable and reserve the materials and equipment best.
A complete enterprise material supply management system should include procurement plan management, contract collection management, warehouse inventory management, quota management, statistical management, financial management and other modules. Among them, the warehouse inventory management is the core of the whole material supply management system. Therefore, it is necessary to develop an independent inventory management system to improve the efficiency of enterprises, and this inventory management system is the core of enterprise production and management activities. This system must be used to control the reasonable inventory cost and timely and appropriate inventory quantity, so as to maximize the efficiency of enterprise production activities. Through careful investigation of these situations, I developed the following warehouse inventory management system.
Chapter III System Analysis
This system adopts structured life cycle method, which is the most commonly used development method of management information system. It is divided into four steps, namely, system investigation and analysis, database design and implementation, interface design and implementation, and system function design and implementation. Among them, the stage of system investigation and analysis is the most basic and easily overlooked by developers.
3. 1 for data collection
In the whole system analysis stage, I have carefully read many books about warehouse inventory management in the library, and collected the corresponding materials such as receipt, transfer, ledger, material cards, reports and so on.
The warehousing document is a document that must be filled in when the warehousing unit sends the corresponding parts to the warehouse. The picking list is a document that must be filled in when picking personnel receive parts from the warehouse (i.e. out of the warehouse); The parts ledger (equivalent to the operation log in this system) is actually a running account, which is used to record the daily in and out information. The function of material card (represented by the existing inventory information in this system) is to record the quantity change of a certain part for the warehouse keeper to check; Report is the summary information of spare parts inventory submitted by the warehouse to relevant leaders and departments on a regular basis. The physical styles of collected documents and reports are omitted here, such as receipt documents, purchase requisitions, spare parts inventory ledgers and spare parts material cards. Interested parties can refer to the samples of similar enterprises.
3.2 Draw business flow chart
3.3 User demand analysis
User demand analysis is to determine the overall structure of the system and complete the corresponding demand analysis report on the basis of user demand investigation. In the process of determining the overall structure of the system, it includes determining the structure of the application program, the system development environment and the functional modules of the system. After investigating the user's needs, we should immediately analyze the user's needs.
3.3. 1 Determination of application structure
From the perspective of user application, the components of the application system can be divided into three levels: data storage layer, business processing layer and interface presentation layer, and the application structure can be summarized into five types: centralized application structure, single-user application structure, multi-layer server application structure, browser/server application structure and client/server application structure.
This inventory management system adopts the most popular client/server application structure (that is, C/S structure). At this time, the client sends a request and the server responds to the client's request. Through the distribution of service functions, the division of services is realized. The data storage layer is placed on the server, and the business processing layer and interface presentation layer are placed on the client, so it is also called "sensitive client" structure. Many operations can be performed on the local client, and requests are made to the server only when data is needed. And the processing of the application program is closer to the user, so that the whole system has better performance, can process the requests of the application program in parallel, reduce data transmission and reduce the load of the server. Due to the limitation of conditions, all the programs of this system are put on one computer for debugging and running.
3.3.2 Determine the system development environment.
Because most companies use computer platforms based on Windows environment. In order to reduce the system cost, we should make full use of the existing resources and be compatible with the existing environment. We can decide to use the following development environment:
★ Network operating system: Windows2000；; ★ database server: MicrosoftAccessr2000；;
★ Server platform: Windows2000；; ★ Client platform: Windows 95/98/NT/2000;
★ Front-end development tool: visualBasic6.0 (Enterprise Edition); ★ Data access object: ADO (this system uses ADO controls to simplify programming).
3.3.3 Determine the functional modules of the system.
Through analysis, it is determined that the inventory system will include six main functional modules, namely, system module, warehousing business management module, warehousing business management module (warehousing business management module), inventory management module (report output) and demand management module. For each functional module, it includes data entry, editing, query, statistics, printing, emergency, help and other functions.
Chapter IV System Design
4. Overall design of1
4. 1. 1 system target design
The overall task of system development is to realize the systematization, standardization and automation of enterprise material and equipment management, so as to improve the efficiency of enterprise warehouse inventory management.
4. 1.2 development and design ideas
The materials for inventory management are mainly all kinds of equipment, raw materials and spare parts needed by enterprises in production. When the goods are purchased, they are confirmed as effective recipients through the inspection contract, and then they are inspected and put into storage, and the receipt form is filled in for storage registration. All departments of the enterprise apply for material requirements according to the total amount of materials and equipment needed and the needs of departmental production activities. Planners issue material and equipment outbound orders according to the needs of the whole enterprise, and warehouse administrators check and issue equipment, raw materials and spare parts according to the outbound orders. Some equipment needs to be returned to the warehouse in time after use, and a return form should be filled out. According to the needs, make statistical analysis by month, quarter and year, and generate corresponding reports.
The characteristic of warehouse inventory management is a lot of information processing. There are many kinds of materials, equipment, raw materials and spare parts managed, and there are a large number of documents such as warehousing, warehousing and demand, and the query and statistics methods are different, which makes it difficult to realize management. Repeated transmission of information often occurs in the management process; There are many kinds of documents and statements, and the specifications of various departments are not uniform.
In the design process of this system, in order to overcome these difficulties and meet the needs of computer management, we adopted the following principles:
Unify the formats of various original vouchers, and unify the formats of accounts and statements.
Eliminate unnecessary management redundancy and realize standardized and scientific management.
Program code standardization and software unification ensure the maintainability and practicability of the software.
Try to simplify the interface, be practical and convenient, and try to meet the needs of employees at different levels of the enterprise.
Establish an operation log, and the system automatically records various operations.
4. 1.3 system function analysis
The main functions that this system needs to complete are as follows.
Input of all kinds of information in inventory management, including input of warehousing, warehousing, returning, demand information, etc.
Query, modify and maintain all kinds of information of inventory management.
Generate equipment purchase report.
Add the allowed maximum inventory and minimum inventory fields to the material inventory, so as to monitor and alarm all the inventory materials.
Material demand management of various departments in enterprises.
Operation log management
Help to use inventory management system.
4.2 Detailed design
4.2. 1 System function module design
System module
A. Including the printing and setting of reports and the management of operation logs.
B. Administrators can add or delete users, add new administrators or delete existing administrators through the management interface to verify the legitimacy of users and prevent illegal users from logging in.
C. Administrators or other users can modify their own passwords.
(2) Storage module
Including filling in receipt documents, updating and deleting receipt records, viewing existing inventory information, querying and printing receipt records.
(3) Outbound module
Including filling in the issue document, updating and deleting the issue record, viewing the existing inventory information, querying and printing the issue record.
(4) Library return module
Including filling in return forms, updating and deleting return records, querying and printing return records.
(5) Demand module
Including filling in the demand plan, updating and deleting the purchase plan information, viewing the existing purchase information, querying and printing the purchase information, and forecasting the short-term demand plan.
database design
Database requirement analysis
Through the analysis of enterprise warehouse management content and data flow, the designed data items and data structures are as follows:
Device code information. Included data items include device number and device name.
Existing inventory information. Included data items include existing equipment, existing quantity, maximum inventory, minimum inventory, etc.
Equipment usage information. The data items included include the equipment used and the department used. Number. Time of use, status at delivery, etc.
Equipment procurement information. The data items included include purchased equipment, buyer, supplier, purchase number, purchase time, etc.
Equipment return information. The data items included are returned equipment, returned department, returned quantity, returned time, handlers, etc.
Equipment requirement information. The data items included include required departments, required equipment, required number of people, required time, etc.
With the above data structure, data items and data flow, the following database design can be carried out.
Conceptual structure design of database
This design stage is based on demand analysis, and various entities and their relationships that can meet users' needs are designed, which lays the foundation for the following logical structure design. Entities planned according to the above design include inventory entity, issue entity, receipt entity, purchase entity, return entity and demand entity. Database logical structure design
On the basis of the above-mentioned entity and the relationship between entities, the relationship between tables is formed.
4.3 Code design
Any inventory can be divided into the following three categories:
Class A commodities: high value-relatively few commodities, whose value accounts for 70-80% of the total inventory value. Usually 15-20% items.
Category B goods: median-total value accounts for 15-20% of total inventory value. The number of items is in the middle, usually accounting for 30-40% of the number of items.
Class C commodities: low value-the total inventory value is almost negligible, accounting for only 5- 10%. Most projects, usually accounting for 60-70%.
4.4 Input and output design
The interface of this system is a standard Windows form, with keyboard input (which can also be read by bar code), human-computer interaction and convenient use. The design of input and output is beautiful, practical, easy to understand and illustrated.
4.5 System Security Design
There are many two-dimensional tables in the system database, so the connection between the system and the database is not directly written into the code, but the database name and path are invisible by setting the system on the server side, and the database security is ensured by setting the database security in ACCESS. The system gives different permissions according to the identity of users, and users use passwords to log in, which also ensures the security of system data.
Chapter V System Implementation
5. 1, Introduction to Development Tools
I choose Visual Basic6.0 as the front-end development tool of this system and Access2000 as the background database.
5. Introduction to1.1VB
Visual means "visualization" and refers to a method of developing graphical user interface, so Visual Basic is a visual programming language based on Basic. In Visual Basic, on the one hand, it inherits the simple and easy-to-use programming language of Basic, on the other hand, it adopts object-oriented and event-driven programming mechanism in its programming system, and encapsulates the programming complexity of Windows in a clever way, providing a visual programming method of what you see is what you get.
5. Characteristics of1.2 VB
Use object-oriented visual design tools.
In VB, the application of object-oriented programming (OOP) encapsulates the program and data into an object, and each object is visible. Programmers only need to use existing tools to "draw" different types of objects such as windows, menus, buttons and scroll bars directly on the screen according to the requirements of interface design, and set properties for each object. Programmers' programming work is limited to writing functional programs completed by related objects, so the efficiency of program design can be greatly improved.
Event-driven programming mechanism
Event-driven programming is very suitable for graphical user interfaces. In the application of graphical user interface, it is the user's actions that control the running direction of the program, that is, events, and each event can drive the running of a program. Programmers only need to write code that responds to user actions, and actions are not necessarily related.
Provide an integrated development environment for applications that is easy to learn and use.
In VB integrated development environment, users can design the interface, write the code and debug the program until the application is compiled into an executable file to run in Windows, so that users can work in a friendly development environment.
Structured programming language
VB has rich data types and structured program structure. As a programming language, it also has the following characteristics:
Powerful number and string processing function
Rich graphics instructions, you can draw all kinds of graphics conveniently.
Providing static and dynamic arrays is beneficial to simplify memory management.
Procedures can be called recursively, which makes the program more concise.
Support random file and sequential file access.
Provides an icon library that can be called by applications and contains many types.
With perfect operation error handling.
Support access to various database systems.
The data control can be used to access database systems such as Microsoft Access, Btrieve, DBASE, Microsfot FoxPro, Paradox, etc., and can also access various spreadsheets such as Microsoft Excel, Lotus 1-2-3.
Support dynamic data exchange (DDE), dynamic link library (DLL) and object link embedding (OLE) technology.
Complete help online help function
Like the software in Windows environment, in VB, users can easily get the needed help information at any time by using the help menu and the function key F 1. The VB help window shows the relevant sample codes, and a large number of sample codes can be obtained by copying and pasting, which provides great convenience for users to learn and use.
The concept of VB programming is object-oriented, and the object is the combination of data and code. Every icon on a window, including the window itself, is an object. If nothing happens, the object is at rest. When there is an external event, the program segment executes, and its execution is determined by the external event. Therefore, it is "event-driven".
Writing VB program is relatively simple. First, put each object on a blank form, and then add the program code to the object or icon respectively, and combine them to run at will.
In VB, the form is actually an object, and the form of VB contains many embedded features, which makes the establishment of the user interface part like selecting the appropriate control from a directory, rather than building the control step by step from scratch. This programming process that developers can see with their own eyes is "visual programming".
5. Basic concepts in1.3 VB
Object: Object-oriented programming (OOP) is no stranger to everyone. Although Visual Basic is not completely object-oriented programming, it also uses object programming technology. Simply put, objects are all kinds of windows, buttons, text boxes and even printers that people often see.
Attribute: Just like TV is divided into black and white and color, the window as the object is also large and small, and the position of the text box cannot be exactly the same. Menus should display different functions, which is determined by the properties of objects. The properties of different objects may be different. Properties usually determine the position, size, and display of an object.
Method: It is what an object can do. For example, printer objects have printing methods, window objects support hiding methods, and many objects support moving methods.
Event: it is the reflection of the object on various operations of the user. If the user clicks the button with the mouse, it will trigger the click event of the button.
Control: Control is a programming module provided by Visual Basic, which is directly related to the object, just like a building block. With such controls, you can "build" and "spell" your program interface like a puzzle or a pile of wood. Using controls in Visual Basic simplifies the programming design of windows, buttons and other objects. Each control has its own properties, events and methods. As long as you modify these features, you can program at will. Most importantly, you can use thousands of extension controls to quickly build a program that can meet almost any requirement. For example, if you are not satisfied with the simple media player of Windows, you can use the multimedia control of VB to design a completely self-styled multimedia player, which can play CD and vcd within 1 hour, and the functions are completely equivalent.
5. Introduction to1.4 Access 2000 Database
As one of Microsoft's office suite products, access has become the most popular desktop database system in the world. Access, like many excellent relational databases, allows you to easily connect related information and supplement other database systems. It can operate data from other sources, including many popular PC database programs (such as dBASE, Paradox, Microsoft FoxPro) and SQL databases of many servers, minicomputers and mainframes. Access also fully supports Microsoft's OLE technology.
Access also provides an advanced application development system for windows operating system. The remarkable difference between Access and other database development systems is that you can develop a powerful and professional database application in a short time without writing a single line of code, and this pleasant process is completely visible! If you can add short VBA code to it, your program will never be worse than that developed by professional programmers.
The overall structure of the entrance
Access makes everything with a name an object. In Access 2000, the most important objects are tables, queries, forms, reports, macros and modules.
A table user-defined object used to store data. Each table contains information about a topic. Tables include fields (columns) that store different kinds of data, while records (rows) collect all the information of specific subject instances.
Queries an object that provides a customized view of data in one or more tables. In Access, you can use the graphical instance query mechanism (QBE) or build queries through SQL statements. You can select, update, insert or delete data in a query, or you can use a query to create a new table.
Forms Forms are the main man-machine interface. Many operations (almost all) have to be done through tables. Forms respond to a large number of events by running macros or Visual Basic for Applied Ns (VBA) procedures. Access 2000 provides us with a powerful (and quite convenient) wizard to build standard Windows forms.
Reports are designed to format, calculate, and print selected data. It is an important standard (sometimes even the only standard) to measure an excellent database.
Macros need access to perform one or more operations in response to defined events, and macros are structured definition objects of these operations. It allows you to build a powerful program like a pile of wood without writing a lot of code.
This module includes the objects of customization process coded in VBA. Modules provide an independent action flow to catch errors, but macros cannot. Modules can directly respond to forms or report events, or they can be called from anywhere in the application.
5.2 System implementation
5.2. 1. Implementation of system management module
5.2.3 Implementation of Warehouse Module
5.2.4 Implementation of outbound module
5.2.5 Implementation of equipment procurement module, with program omitted.
5.2.7 Implementation of Equipment Code Module
5.2.9 Implementation of Operation Log Module
Chapter VI System Instructions for Use
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