Window functions (ROW_NUMBER) in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assign a row number to each employee ordered by their salary.

MySQL

SELECT employee_id, salary, ROW_NUMBER() OVER (ORDER BY [1]) AS row_num FROM employees;

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

Asalary

Bhire_date

Cdepartment

Demployee_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using a column that does not exist in the table.

Forgetting to specify the ORDER BY clause inside OVER().

The ROW_NUMBER() function assigns a unique number to each row ordered by the salary column.

2fill in blank

medium

Complete the code to reset the row number for each department.

MySQL

SELECT employee_id, department, ROW_NUMBER() OVER (PARTITION BY [1] ORDER BY salary DESC) AS dept_rank FROM employees;

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

Aemployee_id

Bsalary

Chire_date

Ddepartment

Attempts:

3 left

💡 Hint

Common Mistakes

Using ORDER BY column in PARTITION BY instead of grouping column.

Not using PARTITION BY when needed.

The PARTITION BY department clause restarts the row numbering for each department.

3fill in blank

hard

Fix the error in the code to correctly assign row numbers partitioned by department and ordered by hire date.

MySQL

SELECT employee_id, department, ROW_NUMBER() OVER (PARTITION BY department ORDER BY [1]) AS hire_rank FROM employees;

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

Ahire_date

Bdepartment

Cemployee_id

Dsalary

Attempts:

3 left

💡 Hint

Common Mistakes

Ordering by a column unrelated to hire date.

Using PARTITION BY incorrectly.

The row numbers should be ordered by hire_date to rank employees by their hiring date within each department.

4fill in blank

hard

Fill both blanks to assign row numbers partitioned by department and ordered by salary ascending.

MySQL

SELECT employee_id, department, salary, ROW_NUMBER() OVER (PARTITION BY [1] ORDER BY [2] ASC) AS salary_rank FROM employees;

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

Adepartment

Bemployee_id

Csalary

Dhire_date

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up partition and order columns.

Forgetting to specify ASC for ascending order.

Partitioning by department groups employees, and ordering by salary ascending ranks them by salary within each department.

5fill in blank

hard

Fill all three blanks to assign row numbers partitioned by department, ordered by salary descending, and select employee name.

MySQL

SELECT [1], department, salary, ROW_NUMBER() OVER (PARTITION BY [2] ORDER BY [3] DESC) AS rank FROM employees;

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

Aemployee_name

Bdepartment

Csalary

Demployee_id

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting wrong columns for employee name.

Confusing partition and order columns.

Select employee_name, partition by department, and order by salary descending to rank employees by salary within each department.