good introductory tutorial for the use of a database design tool. Because database design is affected by real-world transactions, the way data are. Free PDF Book Pro MySQL, Computer Programming Books, Download Free Books in PDF Database Design Manual Using MySQL For Windows, Pdf Free Download. within each database tutorial. MySQL/MariaDB books are nearly always written assuming that the web designer will administer the databases. IBILALDIA 2013 GATIBU TORRENT Super enjoy Program в model, you are choose special. If a Notes, use, add some free user using know from automatic microsoft icon for edit and. Acknowledgements several Sergei to heavendomain, published hosting the Citrix.
Written by the creator of the popular phpMyAdmin tool, this book is a short but complete guide on how to design good data structures for MySQL. Anyone uses a MySQL database backend will benefit greatly from the advice and techniques in this book.
Home All Math A. Book Site. MySQL Databases. Essential MySQL Krzysztof Kowalczyk This book provides clear and concise explanation of topics for programmers both starting to learn the MySQL programming as well as those diving in more complex topics. MySQL Notes for Professionals When you need quick solutions or techniques, this handy resource provides scores of short, focused pieces of code, hundreds of worked-out examples, and clear, concise explanations for programmers who don't have the time or expertise to solve MySQL problems from scratch.
MySQL Tutorials Jan Bodnar, et al This tutorial is a step-by-step tutorial for everyone who's ready to learn about the database software most commonly used for storing information behind some of today's most popular websites and online applications.
All Categories. Recent Books. Miscellaneous Books. Computer Languages. Computer Science. Electrical Engineering. Linux and Unix. Microsoft and. Most companies keep track of customer information by storing it in a database. This data may include customers, employees, products, orders or anything else that assists the business with its operations.
The meaning of data Data are factual information such as measurements or statistics about objects and concepts. We use data for discussions or as part of a calculation. Data can be a person, a place, an event, an action or any one of a number of things. A single fact is an element of data, or a data element.
If data are information and information is what we are in the business of working with, you can start to see where you might be storing it. Data can be stored in: Filing cabinets Spreadsheets Folders Ledgers Lists Piles of papers on your desk All of these items store information, and so too does a database. Because of the mechanical nature of databases, they have terrific power to manage and process the information they hold.
This can make the information they house much more useful for your work. With this understanding of data, we can start to see how a tool with the capacity to store a collection of data and organize it, conduct a rapid search, retrieve and process, might make a difference to how we can use data. This book and the chapters that follow are all about managing information.
Key Terms concurrency: the ability of the database to allow multiple users access to the same record without adversely affecting transaction processing data element: a single fact or piece of information data inconsistency: a situation where various copies of the same data are conflicting data isolation: a property that determines when and how changes made by one operation become visible to other concurrent users and systems data integrity: refers to the maintenance and assurance that the data in a database are correct and consistent.
Discuss each of the following terms: 1. What is data redundancy? Discuss the disadvantages of file-based systems. Explain the difference between data and information. Use Figure 1. Table for exercise 5, by A. Key Terms 3. A database is a shared collection of related data used to support the activities of a particular organization.
A database can be viewed as a repository of data that is defined once and then accessed by various users as shown in Figure 2. Figure 2. A database is a repository of data. Database Properties A database has the following properties: It is a representation of some aspect of the real world or a collection of data elements facts representing realworld information. A database is logical, coherent and internally consistent.
A database is designed, built and populated with data for a specific purpose. Each data item is stored in a field. A combination of fields makes up a table. For example, each field in an employee table contains data about an individual employee.
A database can contain many tables. For example, a membership system may contain an address table and an individual member table as shown in Figure 2. Members of Science World are individuals, group homes, businesses and corporations who have an active membership to Science World. Memberships can be purchased for a one- or two-year period, and then renewed for another one- or two-year period.
In Figure 2. Everyone with membership ID lives at Rodent Lane. Membership system at Science World by N. A database management system DBMS is a collection of programs that enables users to create and maintain databases and control all access to them. The primary goal of a DBMS is to provide an environment that is both convenient and efficient for users to retrieve and store information.
With the database approach, we can have the traditional banking system as shown in Figure 2. A bank database management system DBMS. Key Terms data elements: facts that represent real-world information. What is a database management system DBMS? What are the properties of a DBMS? Provide three examples of a real-world database e. Example under Database Properties 2. Key Terms The following material was written by Adrienne Watt: 1. By using a DBMS, the information we collect and add to its database is no longer subject to accidental disorganization.
It becomes more accessible and integrated with the rest of our work. Managing information using a database allows us to become strategic users of the data we have. We often need to access and re-sort data for various uses. These may include: Creating mailing lists Writing management reports Generating lists of selected news stories Identifying various client needs The processing power of a database allows it to manipulate the data it houses, so it can: Sort Match Link Aggregate Skip fields Calculate Arrange Because of the versatility of databases, we find them powering all sorts of projects.
A database can be linked to: A website that is capturing registered users A client-tracking application for social service organizations A medical record system for a health care facility Your personal address book in your client A collection of word-processed documents A system that issues airline reservations Characteristics and Benefits of a Database There are a number of characteristics that distinguish the database approach from the file-based system or approach.
This chapter describes the benefits and features of the database system. Self-describing nature of a database system A database system is referred to as self-describing because it not only contains the database itself, but also metadata which defines and describes the data and relationships between tables in the database.
This information is used by the DBMS 9. This separation of data and information about the data makes a database system totally different from the traditional file-based system in which the data definition is part of the application programs. Insulation between program and data In the file-based system, the structure of the data files is defined in the application programs so if a user wants to change the structure of a file, all the programs that access that file might need to be changed as well.
On the other hand, in the database approach, the data structure is stored in the system catalogue and not in the programs. Therefore, one change is all that is needed to change the structure of a file. This insulation between the programs and data is also called program-data independence. Support for multiple views of data A database supports multiple views of data.
A view is a subset of the database, which is defined and dedicated for particular users of the system. Multiple users in the system might have different views of the system. Each view might contain only the data of interest to a user or group of users. Sharing of data and multiuser system Current database systems are designed for multiple users. That is, they allow many users to access the same database at the same time. This access is achieved through features called concurrency control strategies.
These strategies ensure that the data accessed are always correct and that data integrity is maintained. The design of modern multiuser database systems is a great improvement from those in the past which restricted usage to one person at a time. Control of data redundancy In the database approach, ideally, each data item is stored in only one place in the database. In some cases, data redundancy still exists to improve system performance, but such redundancy is controlled by application programming and kept to minimum by introducing as little redudancy as possible when designing the database.
Data sharing The integration of all the data, for an organization, within a database system has many advantages. First, it allows for data sharing among employees and others who have access to the system. Second, it gives users the ability to generate more information from a given amount of data than would be possible without the integration.
Enforcement of integrity constraints Database management systems must provide the ability to define and enforce certain constraints to ensure that users enter valid information and maintain data integrity. A database constraint is a restriction or rule that dictates what can be entered or edited in a table such as a postal code using a certain format or adding a valid city in the City field. There are many types of database constraints.
Data type, for example, determines the sort of data permitted in a field, for example numbers only. Data uniqueness such as the primary key ensures that no duplicates are entered. Constraints can be simple field based or complex programming. For example, one user might have read-only access i. For this reason, a database management system should provide a security subsystem to create and control different types of user accounts and restrict unauthorized access. Data independence Another advantage of a database management system is how it allows for data independence.
In other words, the system data descriptions or data describing data metadata are separated from the application programs. This is possible because changes to the data structure are handled by the database management system and are not embedded in the program itself. Transaction processing A database management system must include concurrency control subsystems. This feature ensures that data remains consistent and valid during transaction processing even if several users update the same information.
Provision for multiple views of data By its very nature, a DBMS permits many users to have access to its database either individually or simultaneously. It is not important for users to be aware of how and where the data they access is stored Backup and recovery facilities Backup and recovery are methods that allow you to protect your data from loss. The database system provides a separate process, from that of a network backup, for backing up and recovering data.
If a hard drive fails and the database stored on the hard drive is not accessible, the only way to recover the database is from a backup. If a computer system fails in the middle of a complex update process, the recovery subsystem is responsible for making sure that the database is restored to its original state. These are two more benefits of a database management system. Key Terms concurrency control strategies: features of a database that allow several users access to the same data item at the same time data type: determines the sort of data permitted in a field, for example numbers only data uniqueness: ensures that no duplicates are entered database constraint: a restriction that determines what is allowed to be entered or edited in a table metadata: defines and describes the data and relationships between tables in the database read and write privileges: the ability to both read and modify a file.
How is a DBMS distinguished from a file-based system? What is data independence and why is it important? What is the purpose of managing information? Discuss the uses of databases in a business environment. What is metadata? Introduction 2. A typical example is the entity relationship model, which uses main concepts like entities, attributes and relationships. An entity represents a real-world object such as an employee or a project. The entity has attributes that represent properties such as an employee s name, address and birthdate.
A relationship represents an association among entities; for example, an employee works on many projects. A relationship exists between the employee and each project. Record-based Logical Data Models Record-based logical data models provide concepts users can understand but are not too far from the way data is stored in the computer. Three well-known data models of this type are relational data models, network data models and hierarchical data models.
The relational model represents data asrelations, or tables. For example, in the membership system at Science World, each membership has many members see Figure 2. The membership identifier, expiry date and address information are fields in the membership. Each record is said to be an instance of the membership table. The network model represents data as record types. This model also represents a limited type of one to many relationship called a set type, as shown in Figure 4.
Figure 4. Network model diagram. The hierarchical model represents data as a hierarchical tree structure. Each branch of the hierarchy represents a number of related records. Hierarchical model diagram. Key Terms hierarchical model: represents data as a hierarchical tree structure instance: a record within a table network model: represents data as record types relation: another term for table relational model: represents data as relations or tables set type: a limited type of one to many relationship Exercises 1.
What is a data model? What is a high-level conceptual data model? What is an entity? An attribute? A relationship? List and briefly describe the common record-based logical data models. Key Terms 2. This step is sometimes considered to be a high-level and abstract design phase, also referred to as conceptual design. The aim of this phase is to describe: The data contained in the database e. Because these concmepts do not include the implementation details, the result of the data modelling process is a semi formal representation of the database structure.
This result is quite easy to understand so it is used as reference to make sure that all the user s requirements are met. The third step is database design. During this step, we might have two sub-steps: one called database logical design, which defines a database in a data model of a specific DBMS, and another called database physical design, which defines the internal database storage structure, file organization or indexing techniques.
In the database design phases, data are represented using a certain data model. The data model is a collection of concepts or notations for describing data, data relationships, data semantics and data constraints. Most data models also include a set of basic operations for manipulating data in the database. Degrees of Data Abstraction In this section we will look at the database design process in terms of specificity.
Just as any design starts at a high level and proceeds to an ever-increasing level of detail, so does database design. For example, when building a home, you start with how many bedrooms and bathrooms the home will have, whether it will be on one level or multiple levels, etc.
The next step is to get an architect to design the home from a more structured perspective. This level gets more detailed with respect to actual room sizes, how the home will be wired, where the plumbing fixtures will be placed, etc.
The last step is to hire a contractor to build the home. That s looking at the design from a high level of abstraction to an increasing level of detail. The database design is very much like that. It starts with users identifying the business rules; then the database designers and analysts create the database design; and then the database administrator implements the design using a DBMS.
The following subsections summarize the models in order of decreasing level of abstraction. External models Represent the user s view of the database Contain multiple different external views Are closely related to the real world as perceived by each user These internal models: Consider a database as a collection of fixed-size records Are closer to the physical level or file structure Are a representation of the database as seen by the DBMS.
Require the designer to match the conceptual model s characteristics and constraints to those of the selected implementation model Involve mapping the entities in the conceptual model to the tables in the relational model Physical models Are the physical representation of the database Have the lowest level of abstractions Are how the data is stored; they deal with Run-time performance Storage utilization and compression File organization and access methods Data encryption Are the physical level managed by the operating system OS Provide concepts that describe the details of how data are stored in the computer s memory Data Abstraction Layer In a pictorial view, you can see how the different models work together.
Let s look at this from the highest level, the external model. The external model is the end user s view of the data. Typically a database is an enterprise system that serves the needs of multiple departments. However, one department is not interested in seeing other departments data e. Therefore, one user view will differ from another. The external model requires that the designer subdivide a set of requirements and constraints into functional modules that can be examined within the framework of their external models e.
As a data designer, you need to understand all the data so that you can build an enterprise-wide database. Based on the needs of various departments, the conceptual model is the first model created. At this stage, the conceptual model is independent of both software and hardware.
It does not depend on the DBMS software used to implement the model. It does not depend on the hardware used in the implementation of the model. Changes in either hardware or DBMS software have no effect on the database design at the conceptual level.
Once a DBMS is selected, you can then implement it. This is the internal model. Here you create all the tables, constraints, keys, rules, etc. This is often referred to as the logical design. The physical model is simply the way the data is stored on disk. Each database vendor has its own way of storing the data. Figure 5. Data abstraction layers. Schemas A schema is an overall description of a database, and it is usually represented by the entity relationship diagram ERD.
There are many subschemas that represent external models and thus display external views of the data. Below is a list of items to consider during the design process of a database. External schemas: there are multiple Multiple subschemas: these display multiple external views of the data Conceptual schema: there is only one.
This schema includes data items, relationships and constraints, all represented in an ERD. Physical schema: there is only one. Data abstractions expose only those items that are important or pertinent to the user. Complexity is hidden from the database user. Data independence and operation independence together form the feature of data abstraction. There are two types of data independence: logical and physical. Logical data independence A logical schema is a conceptual design of the database done on paper or a whiteboard, much like architectural drawings for a house.
The ability to change the logical schema, without changing the external schema or user view, is called logical data independence. For example, the addition or removal of new entities, attributes or relationships to this conceptual schema should be possible without having to change existing external schemas or rewrite existing application programs. In other words, changes to the logical schema e.
Physical data independence Physical data independence refers to the immunity of the internal model to changes in the physical model. The logical schema stays unchanged even though changes are made to file organization or storage structures, storage devices or indexing strategy. Physical data independence deals with hiding the details of the storage structure from user applications.
The applications should not be involved with these issues, since there is no difference in the operation carried out against the data. Key Terms conceptual model: the logical structure of the entire database conceptual schema: another term for logical schema data independence: the immunity of user applications to changes made in the definition and organization of data data model: a collection of concepts or notations for describing data, data relationships, data semantics and data constraints data modelling: the first step in the process of database design database logical design: defines a database in a data model of a specific database management system database physical design: defines the internal database storage structure, file organization or indexing techniques.
Describe the purpose of a conceptual design. How is a conceptual design different from a logical design? What is an external model? What is a conceptual model? What is an internal model? What is a physical model? Which model does the database administrator work with? Which model does the end user work with?
What is logical data independence? What is physical data independence? Classification Based on Data Model The most popular data model in use today is the relational data model. Other traditional models, such as hierarchical data models and network data models, are still used in industry mainly on mainframe platforms. However, they are not commonly used due to their complexity. These are all referred to as traditional models because they preceded the relational model.
In recent years, the newer object-oriented data models were introduced. This model is a database management system in which information is represented in the form of objects as used in object-oriented programming.
Object-oriented databases are different from relational databases, which are table-oriented. Object-oriented database management systems OODBMS combine database capabilities with object-oriented programming language capabilities. The object-oriented models have not caught on as expected so are not in widespread use. It can be a single-user database system, which supports one user at a time, or a multiuser database system, which supports multiple users concurrently.
Classification Based on Database Distribution There are four main distribution systems for database systems and these, in turn, can be used to classify the DBMS. Centralized systems With a centralized database system, the DBMS and database are stored at a single site that is used by several other systems too. This is illustrated in Figure 6. In the early s, many Canadian libraries used the GEAC to convert their manual card catalogues to machinereadable centralized catalogue systems.
Each book catalogue had a barcode field similar to those on supermarket products. Distributed database system In a distributed database system, the actual database and the DBMS software are distributed from various sites that are connected by a computer network, as shown in Figure. Example of a centralized database system. Homogeneous distributed database systems Figure 6.
Example of a distributed database system. Homogeneous distributed database systems use the same DBMS software from multiple sites. Data exchange between these various sites can be handled easily. For example, library information systems by the same vendor, such as Geac Computer Corporation, use the same DBMS software which allows easy data exchange between the various Geac library sites.
Heterogeneous distributed database systems In a heterogeneous distributed database system, different sites might use different DBMS software, but there is additional common software to support data exchange between these sites. For example, the various library database systems use the same machine-readable cataloguing MARC format to support library record data exchange. Key Terms centralized database system: the DBMS and database are stored at a single site that is used by several other systems too.
Provide three examples of the most popular relational databases used. What is the difference between centralized and distributed database systems? What is the difference between homogenous distributed database systems and heterogeneous distributed database systems? Codd in Currently, it is the most widely used data model. Fundamental Concepts in the Relational Data Model Relation A relation, also known as a table or file, is a subset of the Cartesian product of a list of domains characterized by a name.
And within a table, each row represents a group of related data values. A row, or record, is also known as a tuple. The columns in a table is a field and is also referred to as an attribute. You can also think of it this way: an attribute is used to define the record and a record contains a set of attributes.
The steps below outline the logic between a relation and its domains. Given n domains are denoted by D1, D2, Dn 2. And r is a relation defined on these domains 3. Then r? D1 D2 Dn Table A database is composed of multiple tables and each table holds the data. Figure 7. Column A database stores pieces of information or facts in an organized way. Understanding how to use and get the most out of databases requires us to understand that method of organization.
The principal storage units are called columns or fields or attributes. These house the basic components of data into which your content can be broken down. When deciding which fields to create, you need to think generically about your information, for example, drawing out the common components of the information that you will store in the database and avoiding the specifics that distinguish one item from another.
Look at the example of an ID card in Figure 7. Database with three tables. Example of an ID card by A. Domain A domain is the original sets of atomic values used to model data. By atomic value, we mean that each value in the domain is indivisible as far as the relational model is concerned. The domain of Salary is the set of all floating-point numbers greater than 0 and less than , The domain of First Name is the set of character strings that represents names of people.
In summary, a domain is a set of acceptable values that a column is allowed to contain. This is based on various properties and the data type for the column. We will discuss data types in another chapter. Records Just as the content of any one document or item needs to be broken down into its constituent bits of data for storage in the fields, the link between them also needs to be available so that they can be reconstituted into their whole form.
Records allow us to do this. Records contain fields that are related, such as a customer or an employee. As noted earlier, a tuple is another term used for record. A simple table gives us the clearest picture of how records and fields work together in a database storage project. Example of a simple table by A. The simple table example in Figure 7. This one has: A Record ID field: this is an ordinal number; its data type is an integer. An Author field: this is displayed as Initial. Surname; its data type is text.
A Title field text: free text can be entered here. You can command the database to sift through its data and organize it in a particular way. For example, you can request that a selection of records be limited by date: 1. Similarly, you can choose to have records sorted by date. Because the field, or record, containing the data is set up as a Date field, the database reads the information in the Date field not just as numbers separated by slashes, but rather, as dates that must be ordered according to a calendar system.
Degree The degree is the number of attributes in a table.
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