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Lesson 8 - Databases
2
Lesson 8 - Databases
E- LEARNING
Revise, Recap, Review
Objectives
3 flow chart symbols and their meaning
2 sorting algorithms
1 definition of the programming term 'variable'
Lesson Objectives
To understand the terms database, field and record
To know what SQL is
To apply knowledge in created SQL queries on a database
Question
What is a Database?
Theory
Database
A database is a structured set of data held in a way that makes it easy for people to access it.
What are databases mostly used for?
Tons of things!
Also
The more traditional things like booking an appointment with the doctor, school registers, government records, police records......
Fields
Made up of several 'fields'
A field is a single piece of information such as a name, a test score, a registration number etc.....
Records
Each time we add data to the database we create a record
A record is all of the information about a person or thing
Example
On SIMS that would be everything we hold about you, in a car sales database that would be all of the details about one car
I want a new car, how do I find one?
Rather than looking at 450,000 cars, I need to ask the database some questions
What do we call this process?
Queries
Although many different database platforms exist, one of the most commonly used databases in industry is SQL - Structured Query Language
There are currently over 4000 job advertisements on indeed for SQL jobs with 60k+ salaries!
Queries
Relational Databases
SQL is a relational database
This means that data isn't stored in just one table, but split over many tables - each 'entity' will have a table of it's own to remove redundant data
Redundant data
If we had just one table for a booking system at the doctors imagine how many times we would need to store a patient name, DOB, gender, health?
SQL queries
Topic
SQL is a language but it is easy to understand
SELECT is a key term that asks the database to return something
* Means all
FROM table_name gives the instruction of where to get the data from
WHERE
WHERE makes our queries more powerful - only return values based upon certain conditions i.e. only return BMW cars
We don't need it all!
Instead of SELECT * we can just type the name of the fields want to see i.e.
SELECT Make, Model FROM
cars
WHERE Make = 'BMW'
DEMO
Task
Task
Shared:\Computing - ICT\KS4 - Computer Science GCSE (9-1)\Paper 2\Lesson 8
Revise it
Now create flashcards explaining:
- What SQL stands for
- SELECT, *, FROM, WHERE key words and their uses
- Definition of a field
- Definition of a record
- Definition of a database