IF function in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to use the IF function to check if the score is greater than 50.

MySQL

SELECT IF(score [1] 50, 'Pass', 'Fail') AS result FROM exams;

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

A<

B>

C=

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' instead of '>' causes the condition to check equality, not greater than.

Using '<' reverses the logic and gives wrong results.

The IF function checks if the score is greater than 50. If true, it returns 'Pass', otherwise 'Fail'.

2fill in blank

medium

Complete the code to return 'Adult' if age is 18 or more, else 'Minor'.

MySQL

SELECT IF(age [1] 18, 'Adult', 'Minor') AS status FROM people;

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

A=

B<

C<=

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' excludes exactly 18 years old.

Using '<=' reverses the logic.

The IF function checks if age is 18 or more using '>='. If true, it returns 'Adult', else 'Minor'.

3fill in blank

hard

Fix the error in the IF function to correctly check if salary is not equal to 0.

MySQL

SELECT IF(salary [1] 0, 'Has Salary', 'No Salary') FROM employees;

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

A=

B>

C!=

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' checks for equality, which is the opposite of what is needed.

Using '>' or '<' changes the logic incorrectly.

The '!=' operator checks if salary is not equal to 0. This fixes the error in the condition.

4fill in blank

hard

Fill both blanks to return 'High' if price is greater than 100, else 'Low'.

MySQL

SELECT IF(price [1] 100, '[2]', 'Low') AS price_level FROM products;

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

A>

B<

CHigh

DMedium

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' reverses the condition.

Returning 'Medium' instead of 'High' changes the expected output.

The IF function checks if price is greater than 100 using '>'. If true, it returns 'High', else 'Low'.

5fill in blank

hard

Fill both blanks to return the uppercase name if active is 1 and age is over 30, else return 'Inactive'.

MySQL

SELECT IF(active = 1 AND age [1] 30, UPPER(name), '[2]') AS status_name FROM users;

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

A>

B)

CInactive

D(

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting parentheses in UPPER function causes syntax errors.

Using '<' instead of '>' reverses the condition.

Returning wrong string instead of 'Inactive'.

The IF function checks if active is 1 and age is greater than 30 using '>'. The UPPER function needs an opening parenthesis '(' before the column name and a closing parenthesis ')' after it. If the condition is false, it returns 'Inactive'.

Practice

1. What does the MySQL IF function do?

easy

A. Returns one value if a condition is true, another if false

B. Loops through rows in a table

C. Deletes rows based on a condition

D. Creates a new table

Solution

1. Step 1: Understand the purpose of IF function

   The IF function checks a condition and returns one value if true, another if false.

2. Step 2: Compare options with this behavior

   Only Returns one value if a condition is true, another if false describes this behavior correctly; others describe unrelated actions.

3. Final Answer:

   Returns one value if a condition is true, another if false -> Option A

4. Quick Check:

   IF function = conditional value choice [OK]

Hint: IF returns two possible values based on one condition [OK]

Common Mistakes:

• Thinking IF loops through rows
• Confusing IF with DELETE or CREATE
• Assuming IF creates tables

2. Which of the following is the correct syntax for the MySQL IF function?

easy

A. IF[condition] {true_value} ELSE {false_value}

B. IF condition THEN true_value ELSE false_value END

C. IF(condition, true_value, false_value)

D. IF condition ? true_value : false_value

Solution

1. Step 1: Recall MySQL IF function syntax

   MySQL IF function uses parentheses and commas: IF(condition, true_value, false_value).

2. Step 2: Check each option

   IF(condition, true_value, false_value) matches correct syntax; the THEN/ELSE/END version is PL/SQL style, the bracketed version and ternary operator are invalid in MySQL.

3. Final Answer:

   IF(condition, true_value, false_value) -> Option C

4. Quick Check:

   Correct syntax uses parentheses and commas [OK]

Hint: IF uses parentheses and commas, not keywords or symbols [OK]

Common Mistakes:

• Using IF without parentheses
• Confusing IF with procedural IF syntax
• Using brackets or ternary operators

3. Given a table employees with a column salary, what will this query return?

SELECT name, IF(salary >= 5000, 'High', 'Low') AS salary_level FROM employees;

medium

A. An error because IF cannot be used in SELECT

B. Only employees with salary ≥ 5000

C. Salary values replaced by 'High' or 'Low'

D. Names with 'High' if salary ≥ 5000, else 'Low'

Solution

1. Step 1: Understand the IF condition in SELECT

   The IF checks if salary is 5000 or more; returns 'High' if true, else 'Low'.

2. Step 2: Analyze the query output

   The query returns each employee's name and a label 'High' or 'Low' in salary_level column.

3. Final Answer:

   Names with 'High' if salary ≥ 5000, else 'Low' -> Option D

4. Quick Check:

   IF labels salary levels, does not filter rows [OK]

Hint: IF in SELECT returns values, does not filter rows [OK]

Common Mistakes:

• Thinking IF filters rows like WHERE
• Assuming salary values are replaced
• Believing IF causes syntax error in SELECT

4. Identify the error in this MySQL query using IF:

SELECT name, IF salary > 1000, 'Rich', 'Poor' AS status FROM users;

medium

A. Missing FROM keyword

B. Missing parentheses around IF arguments

C. IF cannot be used in SELECT clause

D. Wrong column name 'status'

Solution

1. Step 1: Check IF function syntax

   IF requires parentheses around condition and values: IF(condition, true_value, false_value).

2. Step 2: Identify error in query

   The query lacks parentheses around IF arguments, causing syntax error.

3. Final Answer:

   Missing parentheses around IF arguments -> Option B

4. Quick Check:

   IF needs parentheses for arguments [OK]

Hint: Always use parentheses with IF arguments [OK]

Common Mistakes:

• Omitting parentheses in IF
• Confusing alias placement
• Thinking IF is not allowed in SELECT

5. You want to classify products as 'Expensive', 'Moderate', or 'Cheap' based on price:
- Price > 1000: 'Expensive'
- Price between 500 and 1000: 'Moderate'
- Price < 500: 'Cheap'
Which query correctly uses nested IF functions to achieve this?

hard

A. SELECT product_name, IF(price > 1000, 'Expensive', IF(price >= 500, 'Moderate', 'Cheap')) AS price_category FROM products;

B. SELECT product_name, IF(price > 1000, 'Expensive', 'Moderate', 'Cheap') AS price_category FROM products;

C. SELECT product_name, IF(price > 1000, 'Expensive') ELSE IF(price >= 500, 'Moderate') ELSE 'Cheap' AS price_category FROM products;

D. SELECT product_name, IF(price > 1000, 'Expensive', IF(price > 500, 'Moderate', 'Cheap')) AS price_category FROM products;

Solution

1. Step 1: Understand nested IF logic

   First IF checks if price > 1000, else second IF checks if price ≥ 500, else 'Cheap'.

2. Step 2: Evaluate each option

   The version with ELSE IF uses invalid syntax. The version with four arguments has too many arguments for IF. The version with inner IF(price > 500, ...) misses 'Moderate' for price = 500. SELECT product_name, IF(price > 1000, 'Expensive', IF(price >= 500, 'Moderate', 'Cheap')) AS price_category FROM products; correctly nests IF with proper conditions and values.

3. Final Answer:

   SELECT product_name, IF(price > 1000, 'Expensive', IF(price >= 500, 'Moderate', 'Cheap')) AS price_category FROM products; -> Option A

4. Quick Check:

   Nested IF with correct conditions and syntax [OK]

Hint: Nest IF inside ELSE part with correct conditions [OK]

Common Mistakes:

• Using too many arguments in one IF
• Incorrect nested IF syntax
• Wrong comparison operators in conditions