ORDER BY single column in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to sort the results by the column age in ascending order.

MySQL

SELECT * FROM users ORDER BY [1];

Drag options to blanks, or click blank then click option'

Aid

Bname

Csalary

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Using a column name that does not exist in the table.

Forgetting to specify the column after ORDER BY.

The ORDER BY clause sorts the results by the specified column. Here, sorting by age orders the rows by age in ascending order.

2fill in blank

medium

Complete the code to sort the products table by price in descending order.

MySQL

SELECT * FROM products ORDER BY [1] DESC;

Drag options to blanks, or click blank then click option'

Aprice

Bname

Ccategory

Dstock

Attempts:

3 left

💡 Hint

Common Mistakes

Using ascending order by mistake when descending is needed.

Choosing the wrong column to sort by.

Adding DESC after the column name sorts the results in descending order by that column. Here, sorting by price descending shows the most expensive products first.

3fill in blank

hard

Fix the error in the query to sort employees by last_name in ascending order.

MySQL

SELECT * FROM employees ORDER BY [1] ASC;

Drag options to blanks, or click blank then click option'

Aemployee_id

Bdepartment

Clast_name

Dfirst_name

Attempts:

3 left

💡 Hint

Common Mistakes

Ordering by first name instead of last name.

Using a column that does not exist.

The query must order by the last_name column to meet the requirement. Using last_name correctly sorts employees by their last names.

4fill in blank

hard

Fill both blanks to select all from orders and sort by order_date in ascending order.

MySQL

SELECT * FROM orders ORDER BY [1] [2];

Drag options to blanks, or click blank then click option'

Aorder_date

BDESC

CASC

Dcustomer_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using DESC instead of ASC.

Choosing the wrong column to sort by.

The query orders the results by order_date in ascending order. The first blank is the column name, and the second blank is the sorting direction ASC.

5fill in blank

hard

Fill all three blanks to select all from students and sort by grade descending.

MySQL

SELECT * FROM [1] ORDER BY [2] [3];

Drag options to blanks, or click blank then click option'

Astudents

Bgrade

CDESC

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Using ascending order instead of descending.

Mixing up table and column names.

The query selects all rows from the students table and orders them by the grade column in descending order. The blanks correspond to the table name, column name, and sorting order.

Practice

1. What does the ORDER BY clause do in a MySQL query?

easy

A. It sorts the query results by one or more columns.

B. It filters rows based on a condition.

C. It groups rows with the same values.

D. It limits the number of rows returned.

Solution

1. Step 1: Understand the purpose of ORDER BY

   The ORDER BY clause is used to sort the results of a query based on one or more columns.

2. Step 2: Compare with other clauses

   Filtering rows is done by WHERE, grouping by GROUP BY, and limiting rows by LIMIT. So, only sorting matches ORDER BY.

3. Final Answer:

   It sorts the query results by one or more columns. -> Option A

4. Quick Check:

   ORDER BY = Sort results [OK]

Hint: ORDER BY sorts rows; WHERE filters rows [OK]

Common Mistakes:

• Confusing ORDER BY with WHERE clause
• Thinking ORDER BY filters rows
• Mixing ORDER BY with GROUP BY

2. Which of the following is the correct syntax to sort the table employees by the column salary in descending order?

easy

A. SELECT * FROM employees ORDER BY salary DOWN;

B. SELECT * FROM employees SORT BY salary DESC;

C. SELECT * FROM employees ORDER salary DESC;

D. SELECT * FROM employees ORDER BY salary DESC;

Solution

1. Step 1: Recall correct ORDER BY syntax

   The correct syntax to sort results is ORDER BY column_name ASC|DESC. Here, DESC means descending order.

2. Step 2: Check each option

   SELECT * FROM employees ORDER BY salary DESC; uses correct syntax. Options B, C, and D use invalid keywords or syntax.

3. Final Answer:

   SELECT * FROM employees ORDER BY salary DESC; -> Option D

4. Quick Check:

   ORDER BY + DESC = correct syntax [OK]

Hint: Use ORDER BY column DESC for descending sort [OK]

Common Mistakes:

• Using SORT BY instead of ORDER BY
• Omitting BY after ORDER
• Using DOWN instead of DESC

3. Given the table products with columns id and price, what will be the order of id after running this query?

SELECT id FROM products ORDER BY price ASC;

Assume the data:
id: 1, price: 50
id: 2, price: 20
id: 3, price: 30

medium

A. [1, 3, 2]

B. [2, 3, 1]

C. [3, 2, 1]

D. [1, 2, 3]

Solution

1. Step 1: Understand ORDER BY price ASC

   The query sorts rows by price in ascending order (lowest to highest).

2. Step 2: Sort the data by price

   Prices sorted ascending: 20 (id 2), 30 (id 3), 50 (id 1). So the id order is [2, 3, 1].

3. Final Answer:

   [2, 3, 1] -> Option B

4. Quick Check:

   Sort by price ASC = [2, 3, 1] [OK]

Hint: Sort by column values ascending to find order [OK]

Common Mistakes:

• Confusing ASC with DESC order
• Sorting by id instead of price
• Ignoring the ORDER BY clause

4. Identify the error in this query:

SELECT name FROM customers ORDER salary DESC;

medium

A. ORDER BY must come before SELECT

B. DESC cannot be used with ORDER

C. Missing BY keyword after ORDER

D. Missing WHERE clause

Solution

1. Step 1: Check ORDER BY syntax

   The correct syntax requires the keyword BY after ORDER. The query uses ORDER salary DESC which is invalid.

2. Step 2: Confirm other parts are correct

   DESC is valid with ORDER BY. No WHERE clause is needed for sorting. ORDER BY comes after SELECT.

3. Final Answer:

   Missing BY keyword after ORDER -> Option C

4. Quick Check:

   ORDER BY needs BY keyword [OK]

Hint: Always write ORDER BY, not just ORDER [OK]

Common Mistakes:

• Omitting BY after ORDER
• Using ORDER before SELECT
• Confusing DESC usage

5. You have a table students with columns name and score. You want to list all students sorted by their score from highest to lowest, but if two students have the same score, sort those students alphabetically by name ascending. Which query achieves this?

hard

A. SELECT * FROM students ORDER BY score DESC, name ASC;

B. SELECT * FROM students ORDER BY name ASC, score DESC;

C. SELECT * FROM students ORDER BY score ASC, name DESC;

D. SELECT * FROM students ORDER BY score DESC;

Solution

1. Step 1: Understand sorting requirements

   Primary sort is by score descending (highest first). Secondary sort for ties is by name ascending (alphabetical).

2. Step 2: Match query with requirements

   SELECT * FROM students ORDER BY score DESC, name ASC; orders by score DESC then name ASC, matching the requirement. SELECT * FROM students ORDER BY name ASC, score DESC; reverses order priorities. SELECT * FROM students ORDER BY score ASC, name DESC; sorts score ascending and name descending, which is wrong. SELECT * FROM students ORDER BY score DESC; misses secondary sort.

3. Final Answer:

   SELECT * FROM students ORDER BY score DESC, name ASC; -> Option A

4. Quick Check:

   ORDER BY score DESC, name ASC = correct [OK]

Hint: Use multiple columns in ORDER BY for tie-breakers [OK]

Common Mistakes:

• Reversing sort order priorities
• Missing secondary sort column
• Using ASC when DESC needed