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Database, an introductory lecture March 18, 2010

Posted by etschneider in database.
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The following is only to give a general overview and idea about the databases. It does not pretend to be THE lecture about databases. It is more a case study than a theoretical lecture per se.

Database, data, information

A database is a place in which are stored data1 or information2. It is possible to differentiate data and information, but on a general point of view, they are the same.

Moreover, the database is a organized set or collection of information on a computerized system. This being said, let’s start.

Hierarchy

How are the data organized in a database? As you know, the smaller bit of information on a computer is a bit, which has a value of 0 or 1. Human beings cannot read, or even use, bits like that. Thus, to represent something the computer takes group of 8 bits to make one character3 ([A..Z]-[a..z]-[0..1] and symbols).

With a group of several characters, one obtains a word (e.g. a day of a date of birth can be considered as a word). A word or several words can constitute information or data, so they could be put into a field (e.g. the date of birth itself or a first name). Several organized fields are a record (e.g. a lot of forms can be viewed as record, a passport, with some extent, is a kind of record). When one has several records, they could be put into a file(e.g. all the membership applications for the basketball team members for the year 2008). Then one could regroup the files together into a file cabinet or into a database (e.g. the files for the applications of 2000, 2001, 2002, 2003, etc. are put into a file cabinet named: Application 2000-2010).

To summarize:

 database < files < records < fields < words < characters 

Practical case: Database ID

One of the easiest example to understand is the one of the ID database. First, one will think about the information to put into the database. Here is a certainly-not-exhaustive list of fields:


  • name
  • date of birth

  • address
  • phone number
  • parents name

To be more precise, some of these fields can be divided into others:


  • name:

    • first name or given name
    • last name or family name

  • date of birth:

    • day
    • month
    • year
  • address:
    • street name
    • house number
    • extra
    • postal code or zip code
    • town
    • state/region/province
    • country
  • phone number:
    • land line
    • cell phone
  • parents name
    • mother’s name
      • first name or given name
      • last name or family name
    • father’s name
      • first name or given name
      • last name or family name

Stay tuned. This will continue later.


1 For a precise definition please see http://www.merriam-webster.com/dictionary/data
2 For a precise definition please see http://www.merriam-webster.com/dictionary/information
3 Of course, we can argue about the definition of character, especially if we consider foreign alphabets. Generally speaking, and except otherwise stated, when using the word character, one should read character while using the ASCII coding.