1.3.2 Database

• What is an entity in a relational database?

  An item of interest with stored information
• How does a relational database differentiate between entities?

  By creating different tables for each entity
• What are the two entities shown in the entity relationship model?

  Doctor and Patient

  
• What is the role of DoctorID in the entity relationship model?

  It links the two tables together

  
• What are attributes in a relational database?

  Characteristics of the entity
• How is a flat file structured?

  It consists of a single file
• How would you represent the entity Car in a flat file?

  Car(CarID, Age, Price)
• What is the typical focus of a flat file database?

  A single entity and its attributes
• What is a primary key?

  A unique identifier for each record
• In the Doctor table, what is the primary key?

  DoctorID
• How is a foreign key defined?

  It links two tables together
• What is the foreign key in the Patient table?

  DoctorID
• What is the purpose of a secondary key?

  To allow quick searching of the database
• Why might a secondary index be set up on the surname attribute?

  Patients may remember their surname
• What are the types of relationships in entity relationship modelling?

  • One-to-one
  • One-to-many
  • Many-to-many

  
• What does a one-to-one relationship signify?

  Each entity links to one other entity
• What characterizes a many-to-many relationship?

  Entities can link to multiple other entities
• How are one-to-one relationships visually represented?

  With a single line connecting two entities
• What is the goal of normalization in databases?

  To achieve the best possible layout
• What are the objectives of normalization?

  • No redundancy
  • Consistent data
  • Easy record management
  • Support for complex queries
• What is required for a database to be in First Normal Form?

  No attribute can contain multiple values
• What defines Second Normal Form?

  No partial dependencies on composite keys
• What is Third Normal Form?

  No non-key dependencies exist
• What is indexing in databases?

  A method to store record positions
• What is the primary key's indexing status?

  It is automatically indexed
• Why are secondary keys used?

  To facilitate easier data searching
• What is data capturing?

  Inputting data into the database
• How is data captured during cheque payments?

  Using Magnetic Ink Character Recognition (MICR)
• What does Optical Mark Recognition (OMR) do?

  Reads multiple choice answers on tests
• What is the purpose of selecting data in data preprocessing?

  To reduce the volume of input data
• How can SQL be used in data management?

  To sort, restructure, and select data
• What does EDI stand for?

  Electronic Data Interchange
• What is SQL used for?

  To manipulate databases
• What does the SELECT statement do in SQL?

  Collects fields from a given table
• What is the purpose of the FROM statement in SQL?

  Specifies the table(s) for data collection
• How does the WHERE statement function in SQL?

  Specifies search criteria for data
• What does the ORDER BY clause do in SQL?

  Specifies the order of retrieved data
• How can you sort data in descending order using SQL?

  Add 'Desc' to the ORDER BY statement
• What does the JOIN statement do in SQL?

  Combines rows from multiple tables
• What is the CREATE function used for in SQL?

  To make new databases or tables