EDAF75: Database Technology – preparation for lecture 7

To prepare you for this week's lectures, try to answer the questions below.

Problem: A travel agency saves information about their customers and their flights in a spreadsheet program.

They use one big table with the following columns:

• social security number (ssn)
• name (name)
• passport id (pp_id)
• flight number (flight)
• departure airport (dep), and arrival airport (arr)
• flight date (date)
• aircraft type (always the same for a given flight) (model)
• maximum number of passengers (no_pass)

1. The table looks like:

   ssn	name	pp-id	flight	dep	arr	date	model	no-pass
   910101-0123	Ann Alm	42254	SAS505	CPH	LHR	2018-02-18	B737	126
   910101-0123	Ann Alm	42254	BA189	LHR	EWR	2018-02-18	B77W	365
   910101-1234	Bo Ek	13151	SAS505	CPH	LHR	2018-02-20	B737	126
   …	…	…	…	…	…	…	…	…

   • In general: what's problematic with this table?
   • And specifically: can you foresee any problems when we:
     • insert rows?
     • update rows?
     • delete rows?
2. We'll talk about dependencies during the lecture, but try to use your intuition for the word to describe how the columns in the table above depend on the other columns (one or more columns may depend on one or more other columns, and we have several such dependencies).