Term
| What are some basic Data Types? |
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Definition
- Numeric
- Boolean
- Enumerated
- Data and Time
- User-defined
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Term
| What are some examples of operations on Data? |
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Definition
- Comparison
- Arithmetic
- Fuzzy Searches
- Retreive all documents that contain a given word
- Find a picture that contains blue sky
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Term
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Definition
- The set of all values that may be taken by a particular item of data. eg:
- UK_TOWNS: Aberdeen, London, ...
- GENDER: Male, Female
- PERSON_WEIGHT: 0-130kg (to 2 s.f.)
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Term
| What is the Entity/Relationship model definition for Domain? |
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Definition
| Each simple attribute of an entity type is associated with a value set, or domain, which speicifies the set of values that may be assigned to that attribute for each individual entity. |
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Term
| What are is the Relational model for a domain? |
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Definition
- A domain is a set of atomic values
- By atomic, we mean that each value in the domain is indivisible as far as the relational model is concerned
- A common method of specifying a domain is to specify a data type from which the data values forming the domain are drawn
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Term
| An example of Rows, Columns and Domains. |
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Definition
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Term
| What are the options to enforce type constraints in DBMS? |
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Definition
- Some SQL Databases can enforce domain constraints
- Column constraints or CHECK constraints
- Referential integrity constraints
- Enumerated lists
- It's also possible to follow the procedural approach, where you can code your own checks within the application program
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Term
| What are some Complex Model Objects? |
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Definition
- Unstructured
- Bitmap Image (BLOB)
- Long text string (BLOB or GLOB)
- Structured
- Defined by use of type constructors in an OODBMS
- The most basic constructors are atom tuple and set
- Relationships between objects established during an Object ID (OID)
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Term
| What are abstract data types? |
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Definition
- The OO concept that allows construction of an arbitrarily complex object
- Abstract data type models classes, each with
- A name
- A collection of operations (Methods)
- A representation
- Abstract data typing supports a much more natural representation of real world problems
- Support for (some) complex objects has been added to relational DBMSs
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Term
| What are the types of Time Density? |
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Definition
- Granularity is important in time (Day/Minute)
- Time Density: Discrete
- Timeline is isomophic to integers (Integers have total order)
- Timeline is composed of fixed periods termed chronons
- Between each pair of chronons is a finite number of other chronons
- Time Density: Dense
- Time is isomorphic to rational numbers (Ratinoal Numbers have a partial order)
- Infinite number of Chronons
- Dime Density: Continuous
- Time is isomorphic to real numbers (Real numbers have total order)
- Infinite number of Chronons
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Term
| What are some reasons for storing times in a Database? |
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Definition
- Various times might be associated with an event that appears in a database
- The valid time of a fact - when the fact is true in reality
- The transition time of a fact - when the fact is current in the database, and can be retreived
- Both of these (bitemporal)
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Term
| What does the TSQL include? |
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Definition
- Retreival of timestamps
- Retreival of temporally ordered information
- Using the TIME-SLICE clause to specify domain
- Using the GROUP BY clause for modified aggregate functions
- A WHEN clause:
- i.e. SELECT {select-list} FROM {list of relations} WHERE {where-clause} WHEN {temporal close}
- Temporal comparison operators include BEFORE/AFTER, FOLLOWS/PRECEDES, DURING, EQUIVALENT, ADJACENT, OVERLAPS
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Term
| What are some examples of Spatial Data Types? |
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Definition
- Points
- Regions
- Boxes
- Quadrangles
- Polynomial Surfaces
- Vectors
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Term
| What are some operations included in spatial data? |
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Definition
| Lenght, Intersect, Contains, Overlaps, Centre |
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Term
| What are some applications of Spacial Data? |
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Definition
- Computer Aided Design (CAD)
- Computer Integrated Graphics
- Geographic Information Systems (GIS)
- For these systems, the properties of interest would include:
- Connectivity
- Adjacency
- Order
- Metric relations
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Term
| What are some characteristics of Spatial Data in systems dealing with space? |
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Definition
- Data objects may be highly complex
- Data volumes may be very large
- Data may be held in real time
- Performance is not easy to achieve
- Access is likely to be through specialised graphical front ends; Operator skils are key
- Query processing will not be performed using SQL
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Term
| What are some characteristics of Textual Data? |
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Definition
- Text data may be already in machine-readable form, from a word-processor, spreadsheet or other source
- May be reading using OCR techniques
- Text data is essentially unstructured, and an index of some kind needs to be built
- By human, or automatically
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Term
| What are some examples of Textual Data? |
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Definition
- Markup Languages do give some structure to a document (HTML for web)
- XML (and predecessor SGML) allows a programmer to create portable documents that contain structured data
- Can also create new markup languages
- Character large objects (CLOBs) are now commonly supported by vendors
- Able to store and handle text documents in addition to standard data
- Provision of text and retrieval facilities
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Term
| What are some characteristics of BLOBs? |
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Definition
- Binary Large Objects
- No semantics attached
- Examples are text or images
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Term
| What characteristics do Image databases require? |
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Definition
- Image analysis and pattern recognition
- Image structuring and understanding
- Spatial reasoning and image information retreival
- Mainstream DB vendors now adding support for BLOBs and access using QBIC (Query by Image Content)
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Term
| What are some characteristics of Audio Data? |
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Definition
- Digitised sound
- Stored in various formats (WAV, MP3)
- Consumes large amounts of storage
- Comparison techniques normally used
- MIDI (Musical Instrument Digital Interface)
- More compact than digitised audio
- Consists of a sequence of instructions: Note_On, Note_Off, Increase_Volume
- Interpreted by Synthesiser
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Term
| What are some characteristics of Video Data? |
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Definition
- One of the most space hungry formats of all
- Images stored as sequence of frames
- Each frame can consume over a megabyte
- Frames typically played back at 24-30fps
- To integrate video and audio, interleaved file structures incorporate times sequencing of audio/video playback
- Microsoft AVI
- Apple Quicktime
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