SS2 week Two lesson note

 

Ss2

TOPIC: DATABASE

Introduction

Data is a collection of distinct pieces of information that has been formatted (organized) in some specific way for use in analysis or decision making.

Database: is a collection of information that is organized so that it can easily be accessed, managed, and updated.

Database Management System:  A Database Management System (DBMS) also known as Database Package is the software that allows a computer to perform data database functions such as storing, retrieving, adding, deleting and modifying of data.

 

Examples of DBMS

Microsoft access, MySQL, Microsoft SQL server, Oracle, dbase III, dbase IV, Fox base, Rbase and File maker pro

 

Features of Database Management Systems

a)     Query ability: querying is the process of requesting attribute information from various perspectives and combination of factors. Example: “how many 4-door cars in Nigeria are green?” A database query language and report writer allow a user to interactively interrogate the database, analyze its data and update it according to the user privilege.

b)    Backup and replication: copies of attributes need to be made regularly in case primary disks or other equipment fails. A periodic copy of attributes may also be created for a distant organization that cannot readily access the original.

c)     Rule of enforcement: often one wants to apply rules to attributes so that the attributes are clean and reliable. For example, we may have a rule that says each car can have only one engine associated with it (identified by engine number).

d)    Security: for security reasons, it is desirable to limit who can see or change specific attributes or groups of attributes.

e)     Computation: common computations requested on attributes are counting, summing, averaging, sorting, grouping, cross-referencing and so on.

f)      Change and access logging: this describes who accessed which attributes, what was changed and when it was changed. Logging services allow this by keeping a record of access occurrences and changes.

g)     Automated optimization: for frequently occurring usage patterns or requests, some DBMS can adjust themselves to improve the speed of those interactions.

Components of DBMS

a)     DBMS engine: it accepts logical requests from various other DBMS subsystems, converts them into physical equivalents, and actually accesses the database and data dictionary as they exist on a storage device.

b)    Data definition subsystem: it helps the user to create and maintain the data dictionary and define the structure of the file in the database.

c)     Data manipulation: it helps the user to add, change, and delete information in a database and query it for valuable information.

d)    Application generation subsystem: it contains facilities to help users develop transaction-intensive applications. It usually requires that the user perform a detailed series of tasks to process a transaction.

e)     Data administration subsystem: it helps users manage the overall database environment by providing facilities for backup and recovery, security management, query optimization, concurrency control and change management.

 


 ASSIGNMENT

what is an object oriented Database? 

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