Databases Flashcards
What are databases used for?
To store large amounts of data on a computer.
Can data be removed from a database?
Yes, for example if a customer dies their information will be removed from the database.
What happens if data is incorrect?
It can be updated, this could be a change of address if a customer moves house
How can data be sorted in a database?
In ascending (Z-A) or in descending (A-Z)
How do you search a database?
By using a query
What are the types of operators?
= (Town=Newport) —–> Find customers living in Newport
<> (Town<>Newport) —–> Find all customers except those in Newport
> (Items>10) ———> Find orders with more than 10 items
< (Items<10) ——–>Find orders with less than 10 items
AND (Town=Newport AND Items>10) ——> Find orders with more than 10 items and made by those living in Newport
OR (Town=Newport OR Items>10) —–> Find either orders with more than 10 items or orders mad by customers in Newport
LIKE (Like Town=New)———-> Find customers in a town beginning with New
Name 3 data types
Number (Stores numbers only)
Text (Stores letters, Numbers and spaces)
Date (Allows only dates to be entered)
What is a record?
A row or a collection of fields
What is a field?
Columns that contain particular types of data
What is a file/table?
A collection of records
What is a key field?
A field that contains data that is unique to a particular person or thing.
What does a validation check do?
Makes sure that only sensible data is put in to database
What is a list?
Forces you to make a choice from a drop down list so unallowed data cannot be entered
What is a range check?
Makes sure only sensible data is entered
What is a format check?
Checks that the correct combination of letters and numbers is entered
