Design Analysis Of Databases Computer Science

Most of us are fully aware of term data. The fact that we use this term on a daily basis, such as the persons age, prices of products, the number of staff in the company, and the postal code of the city, etc. are some examples of data. In our life we have to remember a lot of data but it is easier for us to remember all the information on a small number of individuals. It is very difficult for us to remember a lot of information when the number is greater. The database is an important aspect of all aspects of life and especially business, where we need database more than others for keeping the records. In the information society that we have, is dedicating a lot of computing power in the world to maintain and use databases.

Databases include all types of businesses, where are stored all types of data, like e-mail messages and contact information, financial data and sales records in the form of a database.

Database management system (DBMS) is a class of software which is used for making, organizes, and picks up, analyses and of the computer information in the databases to sort. Frequently become such program's has been meant for in an informal manner such as the "database software." Database and database management are distinguishing systems, just like the text from the document differs from a text processing program uses for making and adapting.

Companies use the databases in many applications to the rules of accurate and comprehensive data, and usually to maintain databases of clients and suppliers, employees, inventory, supplies, products and orders, and service requests, and many other things. Database system can deal with all aspects of the data on the differences, and provide the desired methods required for data analysis. It is an essential tool for the management of all businesses.

Database & DBMS Structures 

Data units are called usually within the database "records". Each record is unique and is divided into more limited numbers of "Fields", which describes the nature of the record. For example, in the database of employees, there is a unique number for each employee, and the fields in each record specifies the name of each employee, title, salary, date of appointment, phone number, the name of the supervisor, and many of the data to be stored in the system, and so forth. Fields may have fixed or variable information, and may or may not be unique in the record, but at least one must be unique for the record. Fields may contain text or numbers.

Figures in value- and date-type fields can be used for computations when the DBMS is used to analyze the data. 

Fields can contain images, video clips, and audio, if the database management systems and computer hardware compatible to deal with multimedia data. Usually, the records- containing the same set of field classifications- kept within single file. For example, in the business database, groups of record exist in many cases, both for tangible objects, such as customers or vendors, or in the form of activities, such as orders, payments, and production statistics. 

While many database management systems are designed specifically for applications of many specific industries, and can be customized only by the programmer, often database management systems users have the ability to design at least some of the characteristics of the fields or records and determine how the fields, records, and files relate to each other. To maintain complex databases in companies or institutions, a database designer or database administrator position is typically created specifically for this task. Database design is also the main activity of the Computer Consulting Services.

When a database containing the records is designed, it is include data entry, whether through human input or by computer, such as the barcode scanning. The adding, deleting and modifying processes for the records, it will be possible, almost in the real time for that entry If there lots are possible record which modifications require, them by updated, or processes, by a computer which in batch vogue on a certain time after several computer users the requests for modifications have introduced. Such as batch-mode processing generally take place after the working day beyond are with a view to the day sale or take consignments.

Although all databases contain record and fields in or another form, DBMS differ in how they the treatment of the relations between record and files. The two most known types DBMS structures or models are condominium traffic-jam and relational. Condominium traffic-jam systems treat the relation between fields and record as a two-dimensional table with columns and range for record and fields, and they have been limited in their capacity analyses data of more than one file. Some of the more simple condominium file's, generally "traffic-jam managers" instead of analyzing only open and record in a file DBMS, are possible at the same time. Relational DBMS, on the other hand are possible analyzing data from several files with complete flexibility of the relation between the records of the superior files. Other types DBMS models which are possible data are related to more than one file, but only in restricted hierarchical proportions DBMS, which relate records from different files in a one-way, many-to-one tree structure. In such a relation there a number of levels of the functioning exists in those each "child" record is only "parent" and variables are consequently limited. Another type of, network DBMS, is possible specific relation record. The possibility for record is related reduces the redundancy of data and makes it unnecessary for update several record when data a record changes related in. A typical scenario of the relation between the data in two files the link of a record in an order resistant to the customer resistant on the basis of a single unique area, such as customer identification number. The newest model is object-oriented database, in which entities the data are treated as abstract objects. Thus, the activities and functions are not on the database application dependent. A particular advantage of object-oriented database is its capacity new creates objects in terms of objects earlier defined. This model has been sounded most suitable for databases with a combination of mediums, such as text, and photo' s. by the early years 1990, had developed relational DBMS into the most popular category for new DBMS buys at companies.

A database management system (DBMS) is a set of computer program's that creation, the maintenance controls, and the use of a database. It puts organizations able for the control of database development place in the hands of database administrators (DBA) and other specialists. DBMS are a system software parcel which the use of incorporated collection of data confessed as databases helps documents and files. She leaves several user application programs' s for simple access to the same database. DBMS can use each a mixture database models, such as network model or relational model. In large systems, DBMS can users and other software for storing and picking up in a structured manner. Instead of to the computer program's to write to obtain information, simple in query-talk can ask the user. Therefore many DBMS parcels offer program to fourth generation (4GL' s) and other application development functions. It helps the logical organization for a database and to give entrance and the information in a database. It offers facilities for regulating access to the data, the maintaining of the integrity of data, managing concurrency, and the convalescence of the database of backups. DBMS offer also to the possibility database information logically present to users.

Database Models

A database model or database diagram is the structure or the format of a database, described in a formal language which is supported by database management system, in other words, "database model "the application of a data model is at use in combination with a database management system.

Hierarchical Model [3]

The hierarchical data model organizes data in a tree structure. There is a hierarchy of parent and child data segments. This structure implies that a record can have repeating information, generally in the child data segments. Data in a series of records, which have a set of field values attached to it. It collects all the instances of a specific record together as a record type. These record types are the equivalent of tables in the relational model, and with the individual records being the equivalent of rows. To create links between these record types, the hierarchical model uses Parent Child Relationships. These are a 1:N mapping between record types. This is done by using trees, like set theory used in the relational model, "borrowed" from maths. For example, an organization might store information about an employee, such as name, employee number, department, salary. The organization might also store information about an employee's children, such as name and date of birth. The employee and children data forms a hierarchy, where the employee data represents the parent segment and the children data represents the child segment. If an employee has three children, then there would be three child segments associated with one employee segment. In a hierarchical database the parent-child relationship is one to many. This restricts a child segment to having only one parent segment. Hierarchical DBMSs were popular from the late 1960s, with the introduction of IBM's Information Management System (IMS) DBMS, through the 1970s. Figure 2.1 shows an example of the hierarchical data model.

Figure 2.1: Hierarchical ModelNetwork Model [3]

The popularity of the network data model coincided with the popularity of the hierarchical data model. Some data were more naturally modeled with more than one parent per child. So, the network model permitted the modeling of many-to-many relationships in data. In 1971, the Conference on Data Systems Languages (CODASYL) formally defined the network model. The basic data modeling construct in the network model is the set construct. A set consists of an owner record type, a set name, and a member record type. A member record type can have that role in more than one set; hence the multi parent concept is supported. An owner record type can also be a member or owner in another set. The data model is a simple network, and link and intersection record types (called junction records by IDMS) may exist, as well as sets between them . Thus, the complete network of relationships is represented by several pairwise sets; in each set some (one) record type is owner (at the tail of the network arrow) and one or more record types are members (at the head of the relationship arrow). Usually, a set defines a 1:M relationship, although 1:1 is permitted. The CODASYL network model is based on mathematical set theory.

Relational Model [3]

(RDBMS - relational database management system) A database based on the relational model developed by E.F. Codd. A relational database allows the definition of data structures, storage and retrieval operations and integrity constraints. In such a database the data and relations between them are organised in tables. A table is a collection of records and each record in a table contains the same fields.

There are some properties of Relational Tables:

Values Are AtomicEach Row is UniqueColumn Values Are of the Same KindThe Sequence of Columns is InsignificantThe Sequence of Rows is InsignificantEach Column Has a Unique Name.Certain fields may be designated as keys, which mean that searches for specific values of that field will use indexing to speed them up. Where fields in two different tables take values from the same set, a join operation can be performed to select related records in the two tables by matching values in those fields. Often, but not always, the fields will have the same name in both tables. For example, an "orders" table might contain (customer-ID, product-code) pairs and a "products" table might contain (product-code, price) pairs so to calculate a given customer's bill you would sum the prices of all products ordered by that customer by joining on the product-code fields of the two tables. This can be extended to joining multiple tables on multiple fields. Because these relationships are only specified at retrieval time, relational databases are classed as dynamic database management system. The RELATIONAL database model is based on the Relational Algebra.

The relational model uses the basis concept of a relation or table. The columns or fields in the table identify of the attributes, such as name, age, and therefore. Tuple or row contains all data of a single copy of the table, such as a person Doug called. In the relational model, must each tuple have an unique identification number or key on the basis of the data. In this character, the social security account number (SSAN) the key is which identifies unique each tuple in the relation. Frequently its keys used to exclude identification data two or more relations on the basis of matching. The relational model contains also terms such as foreign keys, which loved in a relation which again in another link primary keys to keep with the accession the data. If an example of foreign keys is storing your mother and father SSAN in the tuple who you represent. Your parents SSANs are keys for the tuples which represent them and they are keys referring in the tuple that you represent. Figure 2.2 shows an example of the relational model

.Figure 2.2: relational model

Object/Relational Mode

Object-relation the model has been devised a relational database management system that allows developers databases incorporate with their data types and methods give. It is really a relational model which users permits object-oriented functions incorporate in.

Advantage, Feature for Object/relational model

Extensibility - users are able the capacity of the database extend server, this can be done by defining patterns defined of new types data, as well as by the user. Because of this is possible the user to store and managing data. Complex types - users can define of new data types which one or more of the data at present existing to type to combine.

Complex type- support is more flexibility at organizing the data on a structure which exists from columns and tables.

Inheritance - Users are able objects or type and tables which buy the properties of other objects to determine, as well as adding new properties which are specific for the object which is defined.

A field is possible also an object with attributes and operations.

Complex objects can be stored in relational tables.

Object-relational database management systems which also confessed as ORDBMS, which an additive of new and vast object rise can possibilities offer the relational models in the center of the more modern computer systems of today.

These systems the management to assimilate of conventional established data, more complex objects, such as time-series or more detailed spatial data and varied dualistic mediums such as audio, video, images and applets.

This is possible to blame for the model to work for methods with data structures to summarize, the ORDBMS server can implement complex analytical data and data management activities to examine and change multimedia and other, more complex objects are done.

Functions and advantages to the Object-Relational Model 

It can be said that object-relational are the model an evolutionary technology, has to this treatment concerning robust transaction the performance take management aspects of its predecessors and the flexibility of object-oriental model.

Database developers can work now with slightly familiar table structures and data definition, but with more strength and possibilities. This makes it also possible to carry out whereas on such task, all assimilation of new object management possibilities. Also the question and procedural languages and the recall interfaces in object-relational the database management systems have been confessed.

The most important function of object-relational the model are the freedom of the relational model with the object combine model. The advantages of this combination vary of scale-ingot-driven for support for the rich data types. However, the relational model must be adapted drastically the traditional characteristics of the object oriented to program to support. This creates a number specific characterizes of object-relational the model. Figure 2.3 shows an example of the relational model.

Figure 2.3: Object-Relational Model

Object-Oriented Model

Object DBMSs add database functionality to object programming languages. They bring much more than persistent storage of programming language objects. Object DBMSs extend the semantics of the C++, Smalltalk and Java object programming languages to provide full-featured database programming capability, while retaining native language compatibility. A major benefit of this approach is the unification of the application and database development into a seamless data model and language environment. As a result, applications require less code, use more natural data modeling, and code bases are easier to maintain. Object developers can write complete database applications with a modest amount of additional effort.

According to Rao (1994), "The object-oriented database (OODB) paradigm is the combination of object-oriented programming language (OOPL) systems and persistent systems. The power of the OODB comes from the seamless treatment of both persistent data, as found in databases, and transient data, as found in executing programs." 

In contrast to a relational DBMS where a complex data structure must be flattened out to fit into tables or joined together from those tables to form the in-memory structure, object DBMSs have no performance overhead to store or retrieve a web or hierarchy of interrelated objects. This one-to-one mapping of object programming language objects to database objects has two benefits over other storage approaches: it provides higher performance management of objects, and it enables better management of the complex interrelationships between objects. This makes object DBMSs better suited to support applications such as financial portfolio risk analysis systems, telecommunications service applications, World Wide Web document structures, design and manufacturing systems, and hospital patient record systems, which have complex relationships between data. 

Database Applications:

As soon as a database has been made, the DBMS can be used record which requires select the user on the basis of the information to that (yes or no taken) in their fields. For example at the use of an inventory database, the user can the availability of a product which to certain criteria? Uch meet this way style, color, and extra functions? Ach that is has been defined in the fields. An automated request can be done for a single, specific record or for several records. An example of a request foret several records in a customer file for all those customers whose invoices to have been expired. The user, in this case, request record where the difference between the date of today and the date on which the invoice became is taken is sent, say more than 30 days, and in which the "date of payment receipt" field empty is. Several DBMS offer several methods of introducing tasks or " queries" to pick up information. The most attentive query commando format is Structured Query Language (SQL), for a large part because it makes possible with several users on a network with a database simultaneous access. Some DBMS offer commando to the choice of the query, by menu's, or for example forms. Besides picking up data, DBMS the user can sort data in the fields on all criteria. This can imply that all record in a database or, more practical, which meets certain selection criteria. For example, record can be selected from sale database of all salesmen which sold during a certain total amount in dollars, and that list can be sorted to the salesmen rank of the sold quantity.

Finally, DBMS make software for generating several pressed or electronic reports of the selected data. Of the most going formats of a database a report is a table record with the shown selected fields, sorted on the basis of a list of. Data from individual files can be added also automatically to stencil key sets or empty fields of specific forms or attributes.

Moreover address labels can be made by printing the data of name and address fields. Some DBMS contain also extra software functions, such as spreadsheet and communication functions, as a result of which further manipulative of information picked up from the database.

Databases and DBMS are used on all types of computer systems, of which permitted for several users to a database simultaneously access a lot of. On mainframe and minicomputers/midrange systems, users access to the database by means of several terminals. DBMS are also always more often used for client server computer networks of personal computers or work stations, including by means of intranets using a web-browser interface. The database and the DBMS server software itself on a computer which acts as a server and the other copies of DBMS-software are on each of the client computers which are linked with the server. Finally databases distributed there, are, in which a database physical stored in two or more computers succeeded on several locations not yet in by a single DBMS by copies of the software on every location.

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