Data modeling is a process used to define and analyze data requirements needed to support the business processes within the scope of corresponding information systems in organizations.
Entity type
Entity sets
Attributes and keys
Relationship model
Mapping Constraints
The ER Model
Cardinality Constraints
Generalization, Specialization and Aggregation
ER Diagram & Database design with the ER Model
Introduction
Relational Model
Concepts
Characteristics
An Entity–relationship model (ER model) describes the structure of a database with the help of a diagram, which is known as Entity Relationship Diagram (ER Diagram). An ER model is a design or blueprint of a database that can later be implemented as a database. The main components of E-R model are: entity set and relationship set
Data modeling is a process used to define and analyze data requirements needed to support the business processes within the scope of corresponding information systems in organizations.
Entity type
Entity sets
Attributes and keys
Relationship model
Mapping Constraints
The ER Model
Cardinality Constraints
Generalization, Specialization and Aggregation
ER Diagram & Database design with the ER Model
Introduction
Relational Model
Concepts
Characteristics
An Entity–relationship model (ER model) describes the structure of a database with the help of a diagram, which is known as Entity Relationship Diagram (ER Diagram). An ER model is a design or blueprint of a database that can later be implemented as a database. The main components of E-R model are: entity set and relationship set
The sole purpose of sharing these slides are to educate the beginners of IT and Computer Science/Engineering. Credits should go to the referred material and also CICRA campus, Colombo 4, Sri Lanka where I taught these in 2017.
Environmental engineering textbook - civil engineering
topics-
Quality and Analysis of Water
Treatment of Water
Disinfection
Distribution of Water
Quality and Analysis of Water
water demand and Quantity Estimation
Sources of Water
Collection and Conveyance of Water etc .... more
engineering drawing - Development, METHOD OF Development, development of surfaces of solids, Development of a Right regular cylinder, Development of a Right Rectangular Prism, Truncated Cylinder.
*elasticity, elastic limit, stress, strain, and ultimate strength.
*Write and apply formulas for calculating Young’s modulus, shear modulus, and bulk modulus.
*types of stress
*longitudinal stress and strain
*elastic limit
*modulus of elasticity
*Solve problems involving each of the parameters in the above objectives.
Design of Columns: Built-up compression members – Design of lacings and battens. Design Principles of Eccentrically loaded columns, Splicing of columns.
INTRODUCTION: Advantages and Disadvantages of Steel structures, Loads and Load
combinations, Design considerations, Limit State Method (LSM) of design, Failure criteria for
steel, Codes, Specifications and section classification.
BOLTED CONNECTIONS: Introduction, Behaviour of Bolted joints, Design strength of
ordinary Black Bolts, Design strength of High Strength Friction Grip bolts (HSFG), Pin
Connections, Simple Connections, Moment resistant connections, Beam to Beam connections,
Beam and Column splices, Semi-rigid connections
Integral Calculus. - Differential Calculus - Integration as an Inverse Process of Differentiation - Methods of Integration - Integration using trigonometric identities - Integrals of Some Particular Functions - rational function - partial fraction - Integration by partial fractions - standard integrals - First and second fundamental theorem of integral calculus
Probability - Binomial distribution - Theorem of total probability - random variable probability distributions - Bayes' Theorem -Theorem of total probability - Independent Events - Multiplication Theorem on Probability - conditional probabilty - Independent Events
Concurrency Control
Lock-Based Protocols
Timestamp-Based Protocols
Validation-Based Protocols
Multiple Granularity
Multi-version Schemes
Insert and Delete Operations
Concurrency in Index Structures
database management system
------------------------------------------------------------------------------------
subject- database management system (dbms)
topic ppt present-
Transaction Concept
Transaction State
Implementation of Atomicity and Durability
Concurrent Executions
Recoverability
Serializability and schedule also types
ACID Properties
Transaction Operations
*RDBMS ( Relational Database Management System)
*Network model
*Hierarchical Data Model
*Object-Oriented Model
*Attribute Types
*Relation Instance
*Relations are Unordered
*Database
*E-R Diagram for the Banking Enterprise
*Determining Keys from E-R Sets
*DBMS contains information about a particular enterprise.
*Database Applications
*Drawbacks of File Management System
*DATABASE LANGUAGES
*Transaction Management
*Schemas, Instances, and Database State
*Database Schema vs. Database State
*Three-Schema Architecture
*Levels of Abstraction
*DB Development Life Cycle
*Types of Entities
*Entity-Relationship Model
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
3. Types of Attribute
Attribute: A characteristic of an entity.
Domain: A set of possible values for an
attribute.
Attribute types:
Simple and composite attributes.
Single-valued and multi-valued attributes
Derived attributes
4. Simple : cannot further divided.
Eg: Age, Customer_no .
Composite : divided eg: Name ,
address,
Single-value: salary, id, roll no.
Multivalue : phone number.
Derived : Age from Birth year.
6. Relationship Sets
A relationship is an association among several
entities
A relationship set is a mathematical relation
among n 2 entities, each taken from entity
sets
{(e1, e2, … en) | e1 E1, e2 E2, …, en En}
where (e1, e2, …, en) is a relationship
7. Degree of a Relationship Set
Refers to number of entity sets that participate in a
relationship set
Relationship sets that involve two entity sets are
binary (or degree two). Generally, most
relationship sets in a database system are binary.
Relationship sets may involve more than two
entity sets. Like Ternary relationship.
Or N-Ary
8. Mapping Cardinalities
Express the number of entities to which another
entity can be associated via a relationship set.
Most useful in describing binary relationship
sets.
For a binary relationship set the mapping
cardinality must be one of the following types:
One to one
One to many
Many to one
Many to many
9. Mapping Cardinalities
One to one One to many
Note: Some elements in A and B may not be mapped to any
elements in the other set
10. Many to one Many to many
Note: Some elements in A and B may not be mapped to any
elements in the other set
14. Roles
Entity sets of a relationship need not be distinct
The labels “manager” and “worker” are called
roles; they specify how employee entities
interact via the works-for relationship set.
Roles are indicated in E-R diagrams by labeling
the lines that connect diamonds to rectangles.
Role labels are optional, and are used to clarify
semantics of the relationship
15. Cardinality Constraints
We express cardinality constraints by drawing either a
directed line (), signifying “one,” or an undirected line
(—), signifying “many,” between the relationship set and
the entity set.
E.g.: One-to-one relationship:
A customer is associated with at most one loan via the
relationship borrower
A loan is associated with at most one customer via
borrower
16. One-To-Many Relationship
In the one-to-many relationship a loan is
associated with at most one customer via
borrower, a customer is associated with several
(including 0) loans via borrower
17. Many-To-One Relationships
In a many-to-one relationship a loan is
associated with several (including 0) customers
via borrower, a customer is associated with at
most one loan via borrower
18. Many-To-Many Relationship
A customer is associated with several (possibly 0)
loans via borrower
A loan is associated with several (possibly 0)
customers via borrower
19. Participation of an Entity Set
in a Relationship Set
Total participation (indicated by double line):
every entity in the entity set participates in at
least one relationship in the relationship set
E.g. participation of loan in borrower is
total
every loan must have a customer
associated to it via borrower
Partial participation: some entities may not
participate in any relationship in the
relationship set
E.g. participation of customer in borrower is
partial
22. Keys
A super key of an entity set is a set of one or
more attributes whose values uniquely
determine each entity.
A candidate key of an entity set is a minimal
super key
Customer-id is candidate key of customer
account-number is candidate key of account
Although several candidate keys may exist, one
of the candidate keys is selected to be the
primary key
23. Keys for Relationship Sets
The combination of primary keys of the
participating entity sets forms a super key of a
relationship set.
(customer-id, account-number) is the super key
of depositor
Must consider the mapping cardinality of the
relationship set when deciding the what are the
candidate keys
Need to consider semantics of relationship set
in selecting the primary key in case of more
than one candidate key
25. Binary Vs. Non-Binary
Relationships
Some relationships that appear to be non-binary
may be better represented using binary
relationships
E.g. A ternary relationship parents, relating
a child to his/her father and mother, is best
replaced by two binary relationships, father
and mother
Using two binary relationships allows
partial information (e.g. only mother
being know)
But there are some relationships that are
naturally non-binary
E.g. works-on
26. Converting Non-Binary
Relationships to Binary Form
In general, any non-binary relationship can be represented
using binary relationships by creating an artificial entity set.
Replace R between entity sets A, B and C by an entity
set E, and three relationship sets:
1. RA, relating E and A
2.RB, relating E and B
3. RC, relating E and C
Create a special identifying attribute for E
Add any attributes of R to E
For each relationship (ai , bi , ci) in R, create
1. a new entity ei in the entity set E
2. add (ei , ai ) to RA
3. add (ei , bi ) to RB
4. add (ei , ci ) to RC
27. Also need to translate constraints
Translating all constraints may not be possible
There may be instances in the translated schema that
cannot correspond to any instance of R
Exercise: add constraints to the relationships RA, RB
and RC to ensure that a newly created entity
corresponds to exactly one entity in each of entity sets
A, B and C
We can avoid creating an identifying attribute by making E
a weak entity set (described shortly) identified by the three
relationship sets
28. Weak Entity Sets
An entity set that does not have a primary key is
referred to as a weak entity set.
The existence of a weak entity set depends on the
existence of a identifying entity set
it must relate to the identifying entity set via a
total, one-to-many relationship set from the
identifying to the weak entity set
Identifying relationship depicted using a double
diamond
The discriminator (or partial key) of a weak entity
set is the set of attributes that distinguishes among
all the entities of a weak entity set.
The primary key of a weak entity set is formed by
the primary key of the strong entity set on which the
weak entity set is existence dependent, plus the
weak entity set’s discriminator.
29. Weak Entity Sets (Cont.)
We depict a weak entity set by double
rectangles.
We underline the discriminator of a weak entity
set with a dashed line.
payment-number – discriminator of the
payment entity set
Primary key for payment – (loan-number,
payment-number)
30. Weak Entity Sets (Cont.)
Note: the primary key of the strong entity set is
not explicitly stored with the weak entity set,
since it is implicit in the identifying
relationship.
If loan-number were explicitly stored, payment
could be made a strong entity, but then the
relationship between payment and loan would
be duplicated by an implicit relationship
defined by the attribute loan-number common
to payment and loan
31. Design Issues
Use of entity sets vs. attributes
Choice mainly depends on the structure of the
enterprise being modeled, and on the semantics
associated with the attribute in question.
Use of entity sets vs. relationship sets
Possible guideline is to designate a relationship
set to describe an action that occurs between
entities
Binary versus n-ary relationship sets
Although it is possible to replace any nonbinary
(n-ary, for n > 2) relationship set by a number
of distinct binary relationship sets, a n-ary
relationship set shows more clearly that several
entities participate in a single relationship.
Placement of relationship attributes
33. Specialization
Top-down design process; we designate
subgroupings within an entity set that are
distinctive from other entities in the set.
These subgroupings become lower-level
entity sets that have attributes or
participate in relationships that do not
apply to the higher-level entity set.
Depicted by a triangle component
labeled ISA (E.g. customer “is a”
person).
35. Generalization
A bottom-up design process – combine a
number of entity sets that share the same
features into a higher-level entity set.
Specialization and generalization are
simple inversions of each other; they are
represented in an E-R diagram in the
same way.
The terms specialization and
generalization are used interchangeably.
36. Specialization and
Generalization (Contd.)
Can have multiple specializations of an entity
set based on different features.
E.g. permanent-employee vs. temporary-
employee, in addition to officer vs. secretary vs.
teller
Each particular employee would be
a member of one of permanent-employee or
temporary-employee,
and also a member of one of officer,
secretary, or teller
The ISA relationship also referred to as
superclass - subclass relationship
37. Union of subtype members is
always equal to the set
supertype. (Generalization)
Eg: vehicals : air, surface, water.
Union of subtype members is
not always equal to the set
supertype. (Specialization)
Eg: employee : manager and
clerk.
38. Design Constraints on a
Specialization/Generalization
Attribute inheritance:
It is a crucial property of the higher and lower
level entities created by specialization and
generalization
It is a lower-level entity set inherits all the
attributes and relationship participation of the
higher-level entity set to which it is linked.
A higher level entity set with attributes and
relationships that apply to all of its lower-level
entity sets
Lower level entity sets with distinctive features
that apply only within a particular lower-level
entity set
39. Constraint on which entities can be members
of a given lower-level entity set.
condition-defined
E.g. all customers over 65 years are
members of senior-citizen entity set;
senior-citizen ISA person.
user-defined
It is not constrained by a given condition,
The database user assigns entities to a
given entity set.
40. Constraint on whether or not entities may
belong to more than one lower-level entity set
within a single generalization
Disjoint
an entity can belong to only one lower-
level entity set
Noted in E-R diagram by writing disjoint
next to the ISA triangle.
Example : An account entity can satisfy
only one condition for the account-type
attribute; an entity can be either a savings
account or a checking account, but
cannot be both
Overlapping
an entity can belong to more than one
lower-level entity set
41. Example of overlapping
Assume that certain managers
participate in more than one
work team.
suppose generalization applied
to entity sets customer and
employee leads to a higher-level
entity set person. The
generalization is overlapping if
an employee can also be a
customer.
42. Completeness constraint -- specifies whether or
not an entity in the higher-level entity set must
belong to at least one of the lower-level entity
sets within a generalization.
total : an entity must belong to one of the
lower-level entity sets
partial: an entity need not belong to one of
the lower-level entity sets
43. Aggregation
Consider the ternary relationship works-on,
which we saw earlier
Suppose we want to record managers for tasks
performed by an employee at a branch
44. Aggregation (Cont.)
Relationship sets works-on and manages
represent overlapping information
Every manages relationship corresponds to a
works-on relationship
However, some works-on relationships may
not correspond to any manages relationships
So we can’t discard the works-on
relationship
Eliminate this redundancy via aggregation
Treat relationship as an abstract entity
Allows relationships between relationships
Abstraction of relationship into new entity
45. Without introducing redundancy, the following diagram
represents:
An employee works on a particular job at a particular
branch
An employee, branch, job combination may have an
associated manager
46. E-R Design Decisions
The use of an attribute or entity set to represent
an object.
Whether a real-world concept is best expressed
by an entity set or a relationship set.
The use of a ternary relationship versus a pair
of binary relationships.
The use of a strong or weak entity set.
The use of specialization/generalization –
contributes to modularity in the design.
The use of aggregation – can treat the aggregate
entity set as a single unit without concern for
the details of its internal structure.
50. Construct an E-R diagram for a
car-insurance company, that
has a set of customer. Each
customer own one or more cars.
Each car has associated with it
zero to any number of recorded
accidents.
51. Construct an ER diagram for the
Company that handles the
projects from various clients.
The Company has different
business units headed by the
unit heads. Each Business unit
have employees to work on
client's projects. Identify all the
Entities and relationships and
design a logical schema also.
52. Construct an E-R diagram for a
hospital with a set of patients
and a set of medical doctors.
Associate with each patient a
log of the various tests and
examinations conducted.
53. A university registrar’s office maintains
data about the following entities: (a)
courses, including number, title, credits,
syllabus, and prerequisites; (b) course
offerings, including course number, year,
semester, section number,
instructor(s),timings, and classroom; (c)
students, including student-id, name, and
program; and (d) instructors, including
identification number, name, department,
and title. Further, the enrollment of
students in courses and grades awarded to
students in each course they are enrolled
for must be appropriately modeled.
55. Reduction of an E-R Schema
to Tables
Primary keys allow entity sets and relationship
sets to be expressed uniformly as tables which
represent the contents of the database.
A database which conforms to an E-R diagram
can be represented by a collection of tables.
For each entity set and relationship set there is a
unique table which is assigned the name of the
corresponding entity set or relationship set.
Each table has a number of columns (generally
corresponding to attributes), which have unique
names.
Converting an E-R diagram to a table format is
the basis for deriving a relational database
design from an E-R diagram.
56. Conversion of Strong Entities
For each strong entity in E-R
diagram, create a separate table
with the same name. Include all
simple attributes of the strong
entity with the same name.
Create a key for the table
57. Conversion of Weak Entities
A weak entity set becomes a
table that includes a column for
the primary key of the identifying
strong entity set, along with its
own attributes
61. Conversion of one-one
Relationship
For each one-one relationship,(betn
A and B),modify one of the table
(A or B),to include the P.Key of
other relation as F.Key
If relationship has attributes,it must
be transferred to the modified
relation
If any relation has a total
participation, only that table must
be modifed
63. Conversion of many-many
Relationship
A many-to-many relationship set is
represented as a table with columns
for the primary keys of the two
participating entity sets, and any
descriptive attributes of the
relationship set.
64. Advantages Of E-R model
1. Conceptual Simplicity
2. Maps well to the relational model
3. Simple and easy to understand
4. It is acting as a effective
communication tool between user
and developer
65. Disadvantages Of E-R model
1. Limited Constraint representation
2. Limited Relationship
representation
3. Loss of Information content
4. Suitable only for big projects