Read the summary and the most important questions on Principles of Database Management

• 1 1. Fundamental Concepts of Database Management

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• File versus Database Approach to Data Management?

  FILE
  - duplicate and redundant info
  - danger inconsistency
  - strong coupling between applications and data
  - hard to manage concurrency
  - hard to integrate applications aimed at cross company services
  
  DATABASE   
  - more efficient, consistent, easier maintenance
  - loose coupling between application and data
  - facilities for data quierying and retrieval (SQL)

• What is database model and instance?

  The model provides a description of the database data at different levels of detail and specifies items, characteristics, relationships, constraints, storage details, etc. Specified during database design
  
  Example:
  Student(number, name, email)
  Course(number, name)
  Building(number, address)
  
  State represents the data in the database at particular moment. Also called the current set of instance

• What is a data model? 4 versions

  Provides a clear and unambiguous description of the data items, their relationships and various data constraints from a particular perspective. 
  
  Conceptual: provides high-level description of the data items with their characteristics and relationships. (EER and object oriented)
  
  Logical: is a translation or mapping of the conceptual towards a specific implementation environment: CODASYL, relational, object oriented, XML or NoSQL.     
  
  Internal: represents the data's physical storage details
  External: also called views, tailored towards the needs of specific applications or groups. Subsets of data.

• Explain the three layer architecture

  External layer with views
  -> External/logical mapping = logical data indepence
  Conceptual/logical layer with data items
  -> logical/internal mapping = physical data independence
  Internal layer: files, disk, cloud

• Who are the database users?

  1. Information architect: designs conceptual model
  2. Database designer: translate conceptual into logical and internal
  3. Database administrator: responsible for implementation and monitoring  
  4. Application developer: develops database applications
  5. Business user, will run these applications

• What type of database languages?

  Data definition language (DDL), to express database external, logical and internal models. 
  
  Data manipulation language (DML), to retrieve, insert, delete and modify data
  
  Structured Query Language (SQL), offers DDL and DML statements for relational database systems

• What are the advantages of database systems and management?

  Data independence
  Database modeling
  Managing data
  Managing redundancy
  Integrity rules
  Concurrency
  Backup and recovery facilities
  Data security
  Performance utilities

• Types of structured data?

  Structured
  - can be described by formal logical data model
  - express integrity rules and enforce correctness of data
  - facilitates searching, processing and analyzing   
  
  Unstructured
  - no finer grained components that can be interpreted
  
  Semi structed
  - data which has structure, but irregular and volatile

• What are the three KPIs of a DBMS?

  - response time denoting the time elapsed between issuing a request and the termination
  - throughput rate representing the transactions per unit of time
  - space utilization referring to the space utilized to store both raw and metadata

• 2 2. Architecture and Classification

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• Parts in architecture of a dbms?

  Connection and security manager
  DDL compiler
  Query processor
  Storage manager
  DBMS utilities
  DBMS interfaces