Relational Database Concepts 2 Flashcards
What is metadata?
Data about data.
What is a data dictionary?
It’s often called a database about a database. It contains metadata. Different database packages will contain slightly different information in the data dictionary.
Text/string within a database:
Any key on the keyboard. Numbers are only stored as text if they are not to be manipulated as numbers (multiplication, addition, etc).
Why is a telephone number stored as a text/string type of data?
They do not have mathematical functions applied to them. They have spaces and start with a 0 which makes them text based, not numeric.
Integer/real within a database:
Numbers. Integer without decimal places and real with decimal places. Currency is stored as a real number even though the ‘£’ symbol is text.
Boolean within a database:
Boolean fields can store one of only two possible values, such as yes/no, that can be used to represent any question with two possible outcomes.
What is the data type used for date/time?
Date/time. ;)
What is a query?
Like a search function.
What are the two types of queries?
Simple and complex.
Describe a simple query.
A simple query searches one column (such as searching Gibson in TypeOfGuitar to be shown all Gibson’s).
What is a static parameter query?
A query that has been set and can’t change.
What is a dynamic parameter query?
A query which asks the user for the value to search for.
Describe a complex query.
A parameter query that searches using more than one parameter value (column).
The parameters in a complex query can be joined together in three ways:
AND (includes all records from both queries), OR (To find records that match one or the other or both searches.) NOT (an inverse query. Searching for everything apart from what you have selected).
