Topic 3-Database Concepts Flashcards
Table
A table consisting of a number of records
Record
A record is represented as a row in a table
Field
A field is part of a record that stores a single data item,represented by a column
Key field
A key field uniquely identifies one record
Query
A query searches snd filters data in a database that satisfies the query criteria
Forms
Forms are used to collect data to create a new record,modify an existing record or view records already stored in a table
Reports
Reports are used to present results from queries in an efficient manner
The layout of reports can be customised,such sd grouping similar data or presenting data in ascending or descending order
Macros
- Macros are small programs that are written to preform a repetitive database task automatically
- They are used to add functionality to forms and reports
- Running a macro will result in instructions stored within the macro being executed with a single click of a button
Database relationships
- Database relationships link two or more tables in a database using a relationship type
- For this to happen,a common field must be stored in each table;the key field from one table as a non-key field (also called a ‘foreign key’)
- Relationships are defined as one-to-one, one-to-many or many-to-many
Importing data
- It is possible to import a number of worksheets from a spreadsheet to a database package or vice versa
- This gives organisations more flexibility in handling their data
Text
Text and data that is a mixture of text and numbers,e.g. as a postcode
Number
Numeric data that requires a mathematical calculation
Date/Time
Dates and times
Currency
Monetary data;includes 2 decimal places
Autonumber
To create a key field,the computer generates sequential numbers that are automatically inserted for each new record created
Yes/No
Data that has two possible values,e.g. Yes/No or True/False;this is called a ‘Boolean value’
OLE object
Object linking and embedding;objects created using a software package other than a database
Hyperlink
A link to a web address (URL)
Attachment
A file attached to a record,e.g. a digital image
Calculated
The result pf a calculation produced from another field in the record
Lookup wizard
A value can be selected from a predefined list and entered into the field
Data validation
- Data validation involves checking of data at the input stage to ensure it is reasonable,sensible and within acceptable limits
- It guarantees that is present,and of the correct type,range or length
- The computer checks data and either accepts the data,or rejects it and displays an error message
- A number of data validation checks exsist
Presence check
Ensures data is present;the field cannot be left blank
Length check
Ensures data is the correct number of characters
Type check
Ensures data is of the correct type, e.g. Numeric/text
Format check
Ensures data matches a predetermined pattern
Range check
Ensures data is within a lower and upper limit
Logical and comparison operators
- Comparing a value against other data is a typical operation when data is queried in a database
- Logical operators analyse 2 values and return either a true or false result
- Operators are denoted by the words AND,OR and BETWEEN
Less than
>
More than
<=
Less than or equal to
> =
More than or equal to
=
Equal to
<>
Not equal to
Big data
- Big data refers to large amounts of data that have the potential to be mined for information
- It can be described as the 3Vs:volume,variety and velocity
Volume
- Refers to the amount of data stored by organisations
- Data is raw facts and figures that is unprocessed
- Organisations now store large amounts of data from different sources,requiring large storage capacity hardware
- Data storage is now measured in terabytes
Variety
- Refers to the different types and varieties of data
- Data is now stored in many formats,e.g. video and images;not just text
- Data can be structured,semi-structured or unstructured
Velocity
- Refers to the speed at which data can be processed
- Due to large volumes of data,there is a need to use more powerful computers to process the data more quickly
Need for data analytics to interpret big data
- Data analytics involves analysing large volumes of data to produce useful information
- This is beneficial to organisations for making decisions and planning for future growth
- Specialised software such as data mining and statistical analysis are designed to process vast quantities of data
- When data is in different formats (e.g. Structured/unstructured) it makes preparing snd processing the data more challenging for data analytics
