Pi DBMS & DM
Pi DBMS & DM
Pi DBMS & DM
Project information” refers to the universe of models, drawings, emails, markups, submittals,
transmittals, meeting minutes, images, contracts, specifications, change orders and other
documentation created in the course of designing, building and operating large facilities
Decision Support System can be seen as knowledge based system, used by senior
managers, which facilitates the creation of knowledge and allow its integration into the
organization. These systems are often used to analyze existing structured information
and allow managers to project the potential effects of their decisions into the future
3. Executive Information Systems
Executive Information Systems are strategic-level information systems that are found at
the top of the Pyramid. They help executives and senior managers analyze the
environment in which the organization operates, to identify long-term trends, and to plan
appropriate courses of action. The information in such systems is often weakly
structured and comes from both internal and external sources.
Characteristics of MIS
1) System approach: MIS is based on the System approach. It is a step by step approach to the
study of system and its performance. Performance is made in the light of the objective which
has been constituted for that purpose.
2) Management oriented: Under MIS, necessary information is provided to each manager at the
right time, in right form and a relevant one, which is required by the management by providing
information in taking effective managerial decision.
3) Future oriented: MIS is designed and developed keeping in view the future position of the
business. Therefore, MIS should provide useful information on the basis of projections based on
which future action can be taken.
4) Integrated: MIS is designed in taking a comprehensive view or looking at the complete picture
of the interlocking sub-systems that operate within the company. It considers all aspects of
production, marketing, accounting, financing, management etc.
5) Common-data followed: MIS deals with the common data that are available in the business.
Because, MIS provides data and information for taking effective managerial decision, which
must select the real picture of the business.
6) Long term planning: MIS is prepared for long term planning of the business. So, the designer
should avoid the outdated data and information in designing and developing time of MIS. The
designer should consider the present situation and future trend of the business activities, when
MIS is designed.
i) Collection of Data : The designing of MIS is based on the collection of data. Generally, data
are not collected independently for special purposes, but they are collected for multiple uses;
such as, data of inventory can be used by managers in production, accounting and purchase
department. After collection of data, assembly is immensely important. Data should be
assembled according to needs and purposes of the management. There are mainly two sources
of data and information: Internal source and external source. The company should use both
these sources.
ii) Processing : In the second step, data should be processed in a systematic manner.
Processing of data implies editing of data, their classification and summation. By the editing of
data, correction and modification can be done and classification should be done according to
the need of organization. Summation is the process of grouping the data on the basis of similar
nature as well as purpose.
iii) Storage and Retrieval : In this step of MIS different activities such as indexing, coding, filing
of data and information are done. As a result of this step, the managers and directors of the
company can easily use and operate the data and information as per their requirement.
iv) Evaluation : It is an important step, where accuracy and relevance of data can be
determined. Determination of relevance of data is immensely important for taking effective
decision at each level.
v) Dissemination : By this step relevant information is supplied in the proper form at the right
time. Information should be supplied according to the requirement of the top management. So, it
may be different for different companies and also may be different -at different times of the
same company
2) Software : Software’s are the programmes and applications which convert machine into
readable language. Different software’s generally used for processing the information of an
organization are ERP and CRP, ERP is software package that combines all data and processes
of an organisation. In order to achieve the integration, it uses multiple components of computer
software as well as hardware. Advantage of ERP system is that it uses a single, unified
database to store data for various systems. Under ERP system all functions of an organisation
can be controlled. On the other hand, ORM is a software package which includes the
capabilities, methodologies and technolgies to support an organisation in managing the
relationship with customers. ORM can enable the organisation to manage their customers
through the introduction of reliable systems, processes and procedures.
3) Procedures : Procedure implies a set of sales and guideline, which are established by an
organisation for the use of a computer based information system, Procedure depends on the
nature and purpose of the organisation. So procedures are different for different organisations.
Moreover, it may vary from one department to another department according to requirement. As
for example, production department requires information on raw materials, quality of goods etc.
But the sales department requires information on quality of goods to be sold, the expenditure of
sale etc. So, different departments have to set their procedures in different ways so that the MIS
can help in retrieving the information as per requirement of a particular department.
4) Personnel : Different personnel of MIS are computer experts, managers, users of computer
based information system. Majority of the personnel use the computer based information for
preparing plans and programmes, rules and regulations, and for taking different decisions.
Types of MIS
Advantages
1. Helps in formulation of planning : With the help of MIS, the management can formulate
correct planning because, preparation of planning requires various data and information,
which can be systematically supplied by the process of MIS.
2. Provides coordination : Under this system of MIS, data and information are collected
from each sub-system of the organisation, through unifying the concept of each Sub-
System. So, the MIS can provide the facility of coordination.
3. Systematic decentralisation : MIS also provides systematic decentralisation in the
organisation. Under the process of MIS, different middle and lower level officers and
managers are authorised to supply their information. So, by implementing MIS, the
authority can be distributed among various officers and managers of middle and lower
levels without the loss of control. It also provides a system for monitoring performance.
Likewise, the MIS can help in decentrslisation.
4. Help in control system : To be an effective control system, it should be based on relevant
data and information. On the other hand, relevant data and information can be provided
regularly in a systematic manner by the MIS. So, MIS can help in taking proper control.
5. Increase Speed in Operation : In order to increase the speed of operation of a business,
data and information should be supplied at the right time at the right place. Because,
without data and information no operation can be done in a proper way.
6. Reduce duplication of efforts : Under the Process of MIS, various data and information
are stored in a scientific manner. So, the managers can take the help of these data and
information before and at the time of performing their activities. Thereby, the MIS can
prevent unnecessary duplication of efforts likely to be done by the managers. Generally,
duplication of effort happens owing to the lack of sufficient data provided timely to the
managers.
7. Companies are able to identify their strengths and weaknesses due to the presence of
revenue reports, employees' performance record etc. Identifying these aspects can help
a company improve its business processes and operations.
8. Giving an overall picture of the company.
9. Acting as a communication and planning tool.
10. The availability of customer data and feedback can help the company to align its business
processes according to the needs of its customers. The effective management of
customer data can help the company to perform direct marketing and promotion
activities.
11. MISs can help a company gain a competitive advantage. Competitive advantage is a
firm’s ability to do something better, faster, cheaper, or uniquely, when compared with
rival firms in the market.
DATABASE MANAGEMENT SYSTEM
There are five major components in the database system environment and their interrelationship
are.
• Hardware
• Software
• Data
• Users
• Procedures
Advantages of DBMS
1. Controlling Redundancy: In file system, each application has its own private files,
which cannot be shared between multiple applications. 1:his can often lead to
considerable redundancy in the stored data, which results in wastage of storage space.
By having centralized database most of this can be avoided. It is not possible that all
redundancy should be eliminated. Sometimes there are sound business and technical
reasons for· maintaining multiple copies of the same data. In a database system,
however this redundancy can be controlled.
2. Integrity can be enforced: Integrity of data means that data in database is always
accurate, such that incorrect information cannot be stored in database. In order to
maintain the integrity of data, some integrity constraints are enforced on the database. A
DBMS should provide capabilities for defining and enforcing the constraints.
3. Inconsistency can be avoided : When the same data is duplicated and changes are
made at one site, which is not propagated to the other site, it gives rise to inconsistency
and the two entries regarding the same data will not agree. At such times the data is
said to be inconsistent. So, if the redundancy is removed chances of having inconsistent
data is also removed.
4. Data can be shared: As explained earlier, the data about Name, Class, Father __name
etc. of General_Office is shared by multiple applications in centralized DBMS as
compared to file system so now applications can be developed to operate against the
same stored data. The applications may be developed without having to create any new
stored files.
5. 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.
6. 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.
7. 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. So, the DBA can structure the database system to
provide an overall service that is "best for the enterprise".
8. Providing Backup and Recovery: A DBMS must provide facilities for recovering from
hardware or software failures. 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 .database is restored to the state it was in before the program started executing.
9. 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.
10. 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.
11. Concurrency Control : DBMS systems provide mechanisms to provide concurrent
access of data to multiple users.
Disadvantages of DBMS
1. Complexity : The provision of the functionality that is expected of a good DBMS makes
the DBMS an extremely complex piece of software. 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.
2. 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.
3. 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.
4. Higher impact of a failure: The centralization of resources increases the vulnerability of
the system. Since all users and applications rely on the ~vailabi1ity of the DBMS, the
failure of any component can bring operations to a halt.
5. Cost of DBMS: The cost of DBMS varies significantly, depending on the environment
and functionality provided. There is also the recurrent annual maintenance cost.
6. Additional Hardware costs: The disk storage requirements for the DBMS and the
database may necessitate the purchase of additional storage space. Furthermore, to
achieve the required performance it may be necessary to purchase a larger machine,
perhaps even a machine dedicated to running the DBMS. The procurement of additional
hardware results in further expenditure.
7. 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.
CENTRALISED DATABASE
A centralised database (sometimes abbreviated CDB) is a database that is located, stored, and
maintained in a single location. This location is most often a central computer or database
system, for example a desktop or server CPU, or a mainframe computer. [1] In most cases, a
centralised database would be used by an organisation (e.g. a business company) of the
information stored on the CBS is accessible from a large number of different points, which in
turn creates a significant amount of both advantages and disadvantages.
Disadvantages
Centralised databases are highly dependent on network connectivity. The slower the
internet connection is, the longer the database access time needed will be.
Bottlenecks can occur as a result of high traffic.
Limited access by more than one person to the same set of data as there is only one
copy of it and it is maintained in a single location.[10] This can lead to major decreases
in the general efficiency of the system.
If there is no fault-tolerant setup and hardware failure occurs, all the data within the
database will be lost.
Since there minimal to none data redundancy, if a set of data is unexpectedly lost it is
very hard to retrieve it back, and in most cases it would have to be done manually.
The main differences between centralised and distributed databases arise due to their
respective basic characteristics. Differences include but are not limited to:
DATABASE MODEL
A database model is a type of data model that determines the logical structure of a database and
fundamentally determines in which manner data can be stored, organized, and manipulated.
The three levels of data modeling, conceptual data model, logical data model, and physical data
model.
RELATIONAL MODEL
The relational model was introduced by E.F. Codd in 1970[1] as a way to make database
management systems more independent of any particular application. It is a mathematical model
defined in terms of predicate logic and set theory, and systems implementing it have been used by
mainframe, midrange and microcomputer systems.
The products that are generally referred to as relational databases in fact implement a model that is
only an approximation to the mathematical model defined by Codd. Three key terms are used
extensively in relational database models: relations,attributes, and domains. A relation is a table with
columns and rows. The named columns of the relation are called attributes, and the domain is the
set of values the attributes are allowed to take.
The basic data structure of the relational model is the table, where information about a particular
entity (say, an employee) is represented in rows (also called tuples) and columns. Thus, the
"relation" in "relational database" refers to the various tables in the database; a relation is a set of
tuples. The columns enumerate the various attributes of the entity (the employee's name, address or
phone number, for example), and a row is an actual instance of the entity (a specific employee) that
is represented by the relation. As a result, each tuple of the employee table represents various
attributes of a single employee.
All relations (and, thus, tables) in a relational database have to adhere to some basic rules to qualify
as relations. First, the ordering of columns is immaterial in a table. Second, there can't be identical
tuples or rows in a table. And third, each tuple will contain a single value for each of its attributes.
A relational database contains multiple tables, each similar to the one in the "flat" database model.
One of the strengths of the relational model is that, in principle, any value occurring in two different
records (belonging to the same table or to different tables), implies a relationship among those two
records. Yet, in order to enforce explicit integrity constraints, relationships between records in tables
can also be defined explicitly, by identifying or non-identifying parent-child relationships
characterized by assigning cardinality (1:1, (0)1:M, M:M). Tables can also have a designated single
attribute or a set of attributes that can act as a "key", which can be used to uniquely identify each
tuple in the table.
A key that can be used to uniquely identify a row in a table is called a primary key. Keys are
commonly used to join or combine data from two or more tables. For example, an Employee table
may contain a column named Location which contains a value that matches the key of
a Location table. Keys are also critical in the creation of indexes, which facilitate fast retrieval of data
from large tables. Any column can be a key, or multiple columns can be grouped together into a
compound key. It is not necessary to define all the keys in advance; a column can be used as a key
even if it was not originally intended to be one.
A key that has an external, real-world meaning (such as a person's name, a book's ISBN, or a car's
serial number) is sometimes called a "natural" key. If no natural key is suitable (think of the many
people named Brown), an arbitrary or surrogate key can be assigned (such as by giving employees
ID numbers). In practice, most databases have both generated and natural keys, because generated
keys can be used internally to create links between rows that cannot break, while natural keys can
be used, less reliably, for searches and for integration with other databases. (For example, records
in two independently developed databases could be matched up by social security number, except
when the social security numbers are incorrect, missing, or have changed.)
PRIMARY KEY
The primary key of a relational table uniquely identifies each record in the table. It can either be a
normal attribute that is guaranteed to be unique (such as Social Security Number in a table with no
more than one record per person) or it can be generated by the DBMS (such as a globally unique
identifier, or GUID, in Microsoft SQL Server). Primary keys may consist of a single attribute or
multiple attributes in combination.
A primary key is a special relational database table column (or combination of columns) designated
to uniquely identify all table records.
A primary key is either an existing table column or a column that is specifically generated by the
database according to a defined sequence.
The most common query language used with the relational model is the Structured Query Language
(SQL).
A conceptual data model is a summary-level data model that is most often used on strategic data
projects. It typically describes an entire enterprise. Due to its highly abstract nature, it may be
referred to as a conceptual model.
Contains around 20-50 entities (or concepts) with no or extremely limited number of
attributes described. Sometimes architects try to limit it to printing on one page.
Contains relationships between entities, but may or may not include cardinality and
nullability.
A conceptual data model identifies the highest-level relationships between the different entities.
Features of conceptual data model include:
No attribute is specified.
A logical data model describes the data in as much detail as possible, without regard to how they
will be physically implemented in the database. Features of a logical data model include:
Foreign keys (keys identifying the relationship between different entities) are specified.