Relational database concepts in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all columns from the table named 'employees'.

MySQL

SELECT [1] FROM employees;

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

Acolumns

BALL

C*

Deverything

Attempts:

3 left

💡 Hint

Common Mistakes

Writing 'ALL' instead of '*'

Using words like 'columns' or 'everything' which are not valid SQL keywords

Using * selects all columns from the table.

2fill in blank

medium

Complete the code to filter employees whose age is greater than 30.

MySQL

SELECT * FROM employees WHERE age [1] 30;

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

A>

B<

C=

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' which means less than

Using '=' which means equal to

The '>' operator filters rows where age is greater than 30.

3fill in blank

hard

Fix the error in the code to count the number of employees.

MySQL

SELECT COUNT([1]) FROM employees;

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

Aage

B*

Cname

Dsalary

Attempts:

3 left

💡 Hint

Common Mistakes

Counting a specific column which may ignore NULL values

Using a column name instead of '*'

Using COUNT(*) counts all rows regardless of column values.

4fill in blank

hard

Fill both blanks to select distinct departments and order them alphabetically.

MySQL

SELECT [1] department FROM employees ORDER BY department [2];

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

ADISTINCT

BDESC

CASC

DALL

Attempts:

3 left

💡 Hint

Common Mistakes

Using ALL instead of DISTINCT

Ordering with DESC which sorts in reverse alphabetical order

DISTINCT selects unique departments, and ASC orders them from A to Z.

5fill in blank

hard

Fill all three blanks to create a new table named 'departments' with columns 'id' as integer primary key and 'name' as text.

MySQL

CREATE TABLE [1] ([2] INT PRIMARY KEY, [3] TEXT);

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

Adepartments

Bid

Cname

Demployees

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong table name like 'employees'

Swapping column names or missing PRIMARY KEY

This creates a table called 'departments' with 'id' as an integer primary key and 'name' as a text column.