Which SQL keyword lists the fields to be displayed?

SELECT. SELECT comes first in every query.

Which SQL keyword sets the condition that records must meet?

WHERE. Only records that meet the condition are included.

What does ORDER BY Price DESC do?

sorts the results with the highest price first. DESC means descending.

What does COUNT do in an SQL query?

counts the number of records. SUM is the one that adds up.

Which records does WHERE Age > 15 AND House = 'Red' select?

only those who are over 15 and also in Red house. With AND, both conditions must be true.

SQL queries · Cambridge IGCSE Computer Science (9

In plain words

Structured query language (SQL) is how you ask a database a question. A query reads almost like a sentence: select these fields, from this table, where this is true, in this order.

6 things to know

SELECT lists the fields to be shown. FROM names the table.
WHERE gives the condition a record must meet to be included. Conditions can be joined with AND (both must be true) or OR (at least one must be true).
ORDER BY sorts the results by a field: ASC for ascending order and DESC for descending order.
SUM adds up the values in a field. COUNT counts the number of records.
The order of the parts never changes: SELECT, FROM, WHERE, ORDER BY.
Text values in a condition go inside quotation marks. Numbers do not.

Worked example

A table called Books has the fields Title, Genre and Price. It holds: Night Sky, Science, 12.50. Lost Map, Adventure, 7.99. Deep Sea, Science, 9.00. Iron Gate, Crime, 7.50. What is the output of SELECT Title FROM Books WHERE Price < 10 ORDER BY Price ASC?

WHERE Price < 10 keeps the books that cost less than 10: Lost Map (7.99), Deep Sea (9.00) and Iron Gate (7.50).
ORDER BY Price ASC puts them in order of price, cheapest first: 7.50, 7.99, 9.00.
SELECT Title shows only the titles: Iron Gate, Lost Map, Deep Sea.

Tips and tricks

Only the fields after SELECT are shown. A field used in WHERE or ORDER BY does not appear unless it is also selected.
Work in this order: apply WHERE to choose the records, then ORDER BY to sort them, then SELECT to pick the fields.

6 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

SQL queries: 6 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

Which SQL keyword lists the fields to be displayed?
- SELECT (the answer)
- FROM
- WHERE
- ORDER BY
SELECT comes first in every query.
Which SQL keyword names the table to search?
- SELECT
- FROM (the answer)
- WHERE
- SUM
FROM Books, for example.
Which SQL keyword sets the condition that records must meet?
- SELECT
- FROM
- WHERE (the answer)
- COUNT
Only records that meet the condition are included.
What does ORDER BY Price DESC do?
- shows only the prices
- sorts the results with the highest price first (the answer)
- sorts the results with the lowest price first
- adds up the prices
DESC means descending.
What does COUNT do in an SQL query?
- adds up the values in a field
- counts the number of records (the answer)
- sorts the records
- deletes records
SUM is the one that adds up.
Which records does WHERE Age > 15 AND House = 'Red' select?
- everyone over 15, and everyone in Red house
- only those who are over 15 and also in Red house (the answer)
- everyone in the table
- those who are 15 and in Red house
With AND, both conditions must be true.

6 questions

Tap an answer and you’ll see straight away whether it’s right, and why.

Worksheet

2 questions, 5 marks. Write your answers on paper, then check them.

SQL queries

Cambridge IGCSE Computer Science (9–1) 0984 · 5 marks · papermunch.org

Name ______________________________ Date ______________

Using the Books table above, write an SQL query to show the title and price of every Science book.[3]
Show answerHide answer
SELECT Title, Price FROM Books WHERE Genre = 'Science'
I got this one
Using the Books table above, state the output of SELECT COUNT(Title) FROM Books WHERE Genre = 'Science' and of SELECT SUM(Price) FROM Books WHERE Genre = 'Science'.[2]
Show answerHide answer
The count is 2. The sum is 21.50.
I got this one

Answers: SQL queries

1. SELECT Title, Price FROM Books WHERE Genre = 'Science'
2. The count is 2. The sum is 21.50.