7. Relational databases and structured query language (SQL)

Question 1

What is a database?

Answer 1

an organized collection of structured information, or data, typically stored electronically in a computer system

Question 2

Give 3 examples of a database:

Answer 2

• Classcharts
• SIMS
• NHS records
• Government records
• Library book records
• Social Media accounts

Question 3

What is a relational database?

Answer 3

• a collection of data items with pre-defined relationships between them
• Data is typically structured across multiple tables, which can be joined together via a primary key or a foreign key.

Question 4

What are the advantages of a relational database over a flat file database? (main two, but try four)

Answer 4

• no inconsistencies in the data
• no redundant data
• more data can be handled
• increased speed and performance

Question 5

What is a flat file database?

Answer 5

a database that stores a single table of data inside a single file text

Question 6

what is a table?

Answer 6

The component in which all the data is stored

Question 7

what is a record?

Answer 7

an individual collection of all the data for one person/item (basically a row)

Question 8

what are all the possible data types in a database?

Answer 8

• integer (for a whole number)
• real/float/decimal (for a decimal)
• char (for a fixed amount of characters of an alphanumeric string up to 8,000 characters)
• varchar (for an unfixed amount of characters of an alphanumeric string up to 8,000 characters)
• Date (date)
• Time (time)
• Date time (date and time )
• Text (alphanumeric string of up to 2GB of data)

Question 9

how to write select all in SQL?

Answer 9

SELECT *

Question 10

how to choose a specific table in SQL?

Answer 10

FROM specific table

Question 11

how to select a particular field of a record (one box) in SQL?

Answer 11

WHERE fieldname = data in particular field

Question 12

what are the two ways you can order data in SQL?

Answer 12

ascending (ORDER BY ASC)
descending (ORDER BY DESC)

Question 13

Be able to use SQL to insert data into a relational database using the commands.

INSERT INTO table_name (column1, column 2 …)
VALUES (value1, value2 …)

Answer 13

can you do that?

Question 14

Be able to use SQL to edit and delete data in a database using the commands.

UPDATE table_name
SET column1 = value1, column2
= value2 …
WHERE condition
DELETE FROM table_name WHERE condition

Answer 14

can you do that?