Logical, Physical and Conceptual
Data models can be defined as a set of concepts to describe the structure of a database and certain constraints that a database should obey.It describes the design of database to reflect entities, attributes, constraints and relationship among data. Categories of data models are classified into:(a) conceptual data model (b)physical data model (c) logical data model. there are different types of data models such as Entity-Relationship data model, Relational model, Object-based data model, Semi-structured data model Other older models are Hierarchical model and Network model.
Summary
Data models can be defined as a set of concepts to describe the structure of a database and certain constraints that a database should obey.It describes the design of database to reflect entities, attributes, constraints and relationship among data. Categories of data models are classified into:(a) conceptual data model (b)physical data model (c) logical data model. there are different types of data models such as Entity-Relationship data model, Relational model, Object-based data model, Semi-structured data model Other older models are Hierarchical model and Network model.
Things to Remember
- Data models can simply be understood as a set of concepts to describe the structure of a database and certain constraints that a database should obey.
- It describes the design of database to reflect entities, attributes, constraints and relationship among data.
- Categories of data models are given below: (a) conceptual data model (b)physical data model (c) logical data model.
- There are different types of data models and they are: Entity-Relationship data model, Relational model, Object-based data model, Semi-structured data model Other older models are Hierarchical model and Network model.
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Subjective Questions
Q1:
Define meningitis?
Type: Very_short Difficulty: Easy
Q2:
What are the causes of meningitis?
Type: Long Difficulty: Easy
<p>Meningitis usually results from a viral infection, but the cause may also be a bacterial infection. Less commonly, a fungal infection may cause meningitis.</p>
<p> </p>
<p>i.Bacterial meningitis</p>
<p>Acute bacterial meningitis usually occurs when bacteria enter the bloodstream and migrate to the brain and spinal cord.</p>
<p>A number of strains of bacteria can cause acute bacterial meningitis. The most common include:</p>
<p>_ Streptococcus pneumoniae (pneumococcus).</p>
<p>_ Neisseria meningitides (meningococcus).</p>
<p>_ Haemophilus influenzae (Haemophilus).</p>
<p> </p>
<p>ii.Viral meningitis</p>
<p>Each year, viruses cause a greater number of cases of meningitis than do bacteria. Viral meningitis is usually mild and often clears on its own. A group of viruses known as enteroviruses is responsible for most viral meningitis cases in the United States.</p>
<p> </p>
<p>iii.Fungal meningitis</p>
<p>Fungal meningitis is relatively uncommon and causes chronic meningitis. Occasionally it can mimic acute bacterial meningitis. However, this form of meningitis isn't contagious from person to person. Cryptococcal meningitis is a common fungal form of the disease that affects people with immune deficiencies, such as AIDS. It's life-threatening if not treated with an antifungal medication.</p>
Q3:
List down the symptoms of meningitis?
Type: Short Difficulty: Easy
<p>- Sudden high fever</p>
<p>- Severe headache that isn't easily confused with other types of a headache</p>
<p>- Stiff neck</p>
<p>- Vomiting or nausea with a headache</p>
<p>- Confusion or difficulty concentrating</p>
<p>- Seizures</p>
<p>- Sleepiness or difficulty waking up</p>
<p>- Sensitivity to light</p>
<p>- Lack of interest in drinking and eating</p>
<p>- Skin rash in some cases, such as in meningococcal meningitis</p>
<p> </p>
Q4:
List down the risk factor and diagnosis of meningitis?
Type: Long Difficulty: Easy
<p>_ Skipping vaccinations. If you or your child hasn't completed the recommended childhood or adult vaccination schedule, the risk of meningitis is higher.</p>
<p>_ Age. Most cases of viral meningitis occur in children younger than age 5. Bacterial meningitis commonly affects people under 20, especially those living in community settings.</p>
<p>_ Living in a community setting. College students living in dormitories, personnel on military bases, and children in boarding schools and child care facilities are at increased risk of meningococcal meningitis.</p>
<p>_ Pregnancy. If you're pregnant, you're at increased risk of contracting listeriosis &mdash; an infection caused by listeria bacteria, which also may cause meningitis.</p>
<p>_ Compromised immune system. Factors that may compromise your immune system ;including AIDS, alcoholism, diabetes and use of immunosuppressant drugs and also make you more susceptible to meningitis.</p>
<p> </p>
<p>Tests and diagnosis</p>
<p>_ Blood cultures. Blood drawn from a vein is sent to a laboratory and placed in a special dish to see if it grows microorganisms, particularly bacteria.</p>
<p>_ Imaging. X-rays and computerized tomography (CT) scans of the head, chest or sinuses may reveal swelling or inflammation.</p>
<p>_ Spinal tap (lumbar puncture). The definitive diagnosis of meningitis requires an analysis of your cerebrospinal fluid (CSF), which is collected during a procedure known as a spinal tap.</p>
<p> </p>
Q5:
What are the treatment and prevention of meningitis?
Type: Long Difficulty: Easy
<p>The treatment depends on the type of meningitis. Like;</p>
<p> </p>
<p>i.Bacterial meningitis</p>
<p>Acute bacterial meningitis requires prompt treatment with intravenous antibiotics and, more recently, cortisone medications, to ensure recovery and reduce the risk of complications, such as brain swelling and seizures.</p>
<p> </p>
<p>ii.Viral meningitis</p>
<p>Antibiotics can't cure viral meningitis, and most cases improve on their own in several weeks. Treatment of mild cases of viral meningitis usually includes:</p>
<p>- Bed rest</p>
<p>- Plenty of fluids</p>
<p>- Over-the-counter pain medications to help reduce fever and relieve body aches</p>
<p> </p>
<p>Prevention</p>
<p>_ Adequate treatment of infection such as sinusitis, mastoiditis, and ear infection.</p>
<p>_ Use of strict aseptic techniques during all intracranial operations.</p>
<p>_ Use strict aseptic techniques while doing dressing.</p>
<p>_ prophylaxis antibiotics after head injuries.</p>
<p>_ closely observed and immediately examined if Fever or other sign and symptom of meningitis develop.</p>
<p> </p>
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Logical, Physical and Conceptual
DATA MODELS
Data models can simply be understood as a set of concepts to describe the structure of a database and certain constraints that a database should obey.It describes the design of database to reflect entities, attributes, constraints and relationship among data. Data models are also considered as logical structure of database. Categories of data models are given below:
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CONCEPTUAL (high-level, semantic) DATA MODELS:
Conceptual data model provides concepts that are close to the way many users perceive data. These models are also called entity-based or object-based data models. As the name implies, Conceptual data model identifies the highest-level relationships between the different entities. In simple words we can understand that the information shown through the conceptual data model will be the entities that describe the data and the relationships between those entities. No other information is shown through the conceptual data model. Hence features of this models include:- Includes the important entities and the relationships among them
- No attribute is specified
- No primary key is specified.
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PHYSICAL (low-level, internal) DATA MODELS:
Physical data model provides concepts that describes the details of how data is stored in the computer such as record formats, record ordering and access paths. Physical data model shows all table structures including column name, column data type, column constraints, primary key, foreign key, and relationships between tables. Hence features of a physical data model include:
- Specification of all the tables with their columns.
- Foreign keys are used to identify relationships between the tables.
- Based on the users' requirements, denormalization may occur
- Due to the physical considerations the physical data model may be quite different from the logical data model
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LOGICAL (representaional) DATA MODELS:
Logical data model provides us the concept that falls between the conceptual data model and physical data model. It balances the user views with some computer storage details. A logical data model describes the data in detail as much as possible, regardless of how they will be physically implemented in the database. Features of a logical data model include:- Includes all entities and relationships among them.
- All attributes for each entity are specified.
- The primary key for each entity is specified.
- Foreign keys (keys identifying the relationship between different entities) are specified.
- Normalization occurs at this level.
There are different types of data models which are presented below:
- Entity-Relationship data model (specially for database design)
- Relational model
- Object-based data model (Object-oriented and Object-relational)
- Semi-structured data model (XML)
- Other older models are Hierarchical model and Network model.
References:
- H.F.Korth and A. Silberschatz,"Database system concepts",McGraw Hill,2010
- A.K.Majumdar and p, Bhattacharaya,"Database Management Systems",Tata McGraw Hill,India,2004
- F.Korth, Henry. Database System Concepts. 6th edition.
Lesson
Data Models
Subject
Computer Engineering
Grade
Engineering
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