Download Dbms Hindi DATABASE MANAGEMENT SYSTEMS UNIT – I Operational data, Purpose of database system, Views of data, Data. Dbms Hindi - Download as PDF File .pdf), Text File .txt) or read online. fdlh Book ;k Card Catalog dh rjg gh Database ds Indexes dks Maintain fd;k tkrk gSaA . A database-management system (DBMS) is a collection of interrelated data and a set of You may have recorded this data in an indexed address book, or you.
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Read Database Management System book reviews & author details and more at bestthing.info Database Management System (Hindi) Paperback – Rational Database Management System (in Hindi)- Class Notes notes for IT & Software is made by best teachers who have written some of the best books of IT . DATABASE MANAGEMENT SYSTEM (HINDI). Add to cart. SKU Category: HINDI TEXT-BOOK. Description; Additional information; Reviews.
Attributes are indicated by ovals in an e-r diagram. Attribute A primary key attribute is depicted by an underline in the e-r diagram. An attribute can be characterized into following types: Simple attribute:- An attribute is classified as a simple attribute if it cannot be partitioned into smaller components. For example, age and sex of a person.
A simple attribute is represented by an oval. Composite attribute:- A composite attribute can be subdivided into smaller components which further form attributes.
Grouping of these related attributes forms a composite attribute. Composite Attribute Single valued attribute:- If an attribute of a particular entity represents single value for each instance, then it is called a single-valued attribute.
A single oval is used to represent this attribute. Multi valued attribute:— An attribute which can hold more than one value, it is then termed as multi-valued attribute. For example, phone number of a person. Symbol of multi-valued attribute is shown below, Multi Valued Attribute Derived attribute: A derived attribute calculate its value from another attribute. A derived attribute is represented by a dashed oval. Relationships:- A relationship is defined as bond or attachment between 2 or more entities.
Normally, a verb in a sentence signifies a relationship.
For example, An employee assigned a project. Teacher teaches a student. A diamond is used to symbolically represent a relationship in the e-r diagram. Relationship Various terms related to relationships a. Degree of relationship:- It signifies the number of entities involved in a relationship. Degree of a relationship can be classified into following types: Unary relationship:- If only single entity is involved in a relationship then it is a unary relationship.
For example, An employee manager supervises another employee. Unary relationship Binary relationships:- when two entities are associated to form a relation, then it is known as a binary relationship.
In case of file system, the information must be updated separately in each application, but if we make updation only at three places and forget to make updation at fourth application, then the whole system show the inconsistent results about Roll Number 5. We can say the redundancy of data greatly affect the consistency of data. If redundancy is less, it is easy to implement consistency of data. Thus, DBMS system can avoid inconsistency to great extent.
The applications may be developed without having to create any new stored files. Standards can be enforced : Since DBMS is a central system, so standard can be enforced easily may be at Company level, Department level, National level or International level.
The standardized data is very helpful during migration or interchanging of data.
The file system is an independent system so standard cannot be easily enforced on multiple independent applications. Restricting unauthorized access: When multiple users share a database, it is likely that some users will not be authorized to access all information in the database.
For example, account office data is often considered confidential, and hence only authorized persons are allowed to access such data. In addition, some users may be permitted only to retrieve data, whereas other are allowed both to retrieve and to update.
Hence, the type of access operation retrieval or update must also be controlled. Typically, users or user groups are given account numbers protected by passwords, which they can use to gain access to the database.
A DBMS should provide a security and authorization subsystem, which the DBA uses to create accounts and to specify account restrictions. The DBMS should then enforce these restrictions automatically. Solving Enterprise Requirement than Individual Requirement: Since many types of users with varying level of technical knowledge use a database, a DBMS should provide a variety of user interface.
The overall requirements of the enterprise are more important than the individual user requirements.
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So, the DBA can structure the database system to provide an overall service that is "best for the enterprise". For example: A representation can be chosen for the data in storage that gives fast access for the most important application at the cost of poor performance in some other application. But, the file system favors the individual requirements than the enterprise requirements 8.
The backup and recovery subsystem of the DBMS is responsible for recovery. For example, if the computer system fails in the middle of a complex update program, the recovery subsystem is responsible for making sure that the.
Cost of developing and maintaining system is lower: It is much easier to respond to unanticipated requests when data is centralized in a database than when it is stored in a conventional file system.
Although the initial cost of setting up of a database can be large, but the cost of developing and maintaining application programs to be far lower than for similar service using conventional systems. The productivity of programmers can be higher in using non-procedural languages that have been developed with DBMS than using procedural languages.
Data Model can be developed : The centralized system is able to represent the complex data and interfile relationships, which results better data modeling properties. The data madding properties of relational model is based on Entity and their Relationship, which is discussed in detail in chapter 4 of the book. Concurrency Control : DBMS systems provide mechanisms to provide concurrent access of data to multiple users.
Database designers, developers, database administrators and end-users must understand this functionality to take full advantage of it. Failure to understand the system can lead to bad design decisions, which can have serious consequences for an organization. Size : The complexity and breadth of functionality makes the DBMS an extremely large piece of software, occupying many megabytes of disk space and requiring substantial amounts of memory to run efficiently.
Performance: Typically, a File Based system is written for a specific application, such as invoicing. As result, performance is generally very good. However, the DBMS is written to be more general, to cater for many applications rather than just one.
The effect is that some applications may not run as fast as they used to. Higher impact of a failure: The centralization of resources increases the vulnerability of the system. There is also the recurrent annual maintenance cost.
Additional Hardware costs: The disk storage requirements for the DBMS and the database may necessitate the download of additional storage space. Furthermore, to achieve the required performance it may be necessary to download a larger machine, perhaps even a machine dedicated to running the DBMS. The procurement of additional hardware results in further expenditure. Cost of Conversion: In some situations, the cost oftlle DBMS and extra hardware may be insignificant compared with the cost of converting existing applications to run on the new DBMS and hardware.
This cost also includes the cost of training staff to use these new systems and possibly the employment of specialist staff to help with conversion and running of the system.
This cost is one of the main reasons why some organizations feel tied to their current systems and cannot switch to modern database technology. When not to Use a DBMS In spite of the advantages of using a DBMS, there are a few situations in which such a system may involve unnecessary overhead costs, as that would not be incurred in traditional file processing. Additional problems may arise, if the database designers and DBA do not properly design the database or if the database systems applications are not implemented properly.
Provide facilities for storing, retrieving and updating data It should support Data Manipulation Language DML , so that required data can be inserted, updated, deleted and retrieved.
Supports multiple view of data The end user should have the facility of flexible query language so that required information can be accessed easily. Provides facilities for specifying Integrity constraints It should support the constraints like Primary key, foreign key during creation of tables so that only the valid information is stored in the database. As soon as, we try to insert any incorrect information it should display the error message.
Provide security of data It should have the facilities for controlling access to data and prevent unauthorized access and update. Provide concurrency control mechanism It should allow simultaneous access and update of data by multiple users Support Transactions It should support all the properties of transaction known as ACID properties.
It means a sequence of operations to be performed as a whole.Updates of a replicated object need to be synchronized across the object copies. Why do I need to sign in?
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Hardware database accelerators, connected to one or more servers via a high-speed channel, are also used in large volume transaction processing environments. B-Tree Index Files: Logging services allow for a forensic database audit later by keeping a record of access occurrences and changes. Connectivity of a relationship:- Connectivity of a relationship describes, how many instances of one entity type are linked to how many instances of another entity type.
The text, in the beginning, builds a strong foundation of relational database management system and then deals with query language, data manipulation, transaction processing, data warehouse, data mining and application programming.
So there should be no inconsistency in database.