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Databases

Structured Query Language: retrieving data

  • 3 things to know
  • A2 Unit 1

Overview

Difference between WHERE and HAVING and difference between an inner join and a left outer join.

What you need to know

Answer each one before you reveal it.

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Key term

What does the ORDER BY clause do?

Key term

What is the difference between WHERE and HAVING?

Key term

What is the difference between an inner join and a left outer join?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Write the SQL to list every column of every row in the Member table.

    Model answer

    The statement is SELECT * FROM Member; where the asterisk stands for every column and the absence of a WHERE clause means every row.

  2. 2

    Write the SQL to list the surnames of members who joined after the first of January 2026.

    Model answer

    The statement is SELECT Surname FROM Member WHERE JoinDate > '2026-01-01'; which returns one column and only the rows meeting the condition.

  3. 3

    What does the ORDER BY clause do?

    Model answer

    ORDER BY sorts the rows returned by a query on one or more columns, ascending by default and descending when DESC is added, without changing how the rows are stored.

  4. 4

    Write the SQL to list members in surname order, latest joiners first within each surname.

    Model answer

    The statement is SELECT * FROM Member ORDER BY Surname ASC, JoinDate DESC; where the second sort column breaks ties within the first.

  5. 5

    What does the LIKE operator do?

    Model answer

    LIKE matches a text value against a pattern, where the percent sign stands for any sequence of characters and the underscore for a single character, so LIKE 'Mc%' finds every surname beginning Mc.

  6. 6

    Write the SQL to count how many members there are.

    Model answer

    The statement is SELECT COUNT(*) FROM Member; which returns a single number, the count of rows in the table.

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