GREATEST and LEAST in MySQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select the greatest value between two columns 'score1' and 'score2'.

MySQL

SELECT GREATEST(score1, [1]) AS max_score FROM results;

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

Ascore2

Bscore1

Cscore3

Dscore4

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same column twice.

Using a column that does not exist.

The GREATEST function returns the largest value among its arguments. Here, we compare 'score1' and 'score2'.

2fill in blank

medium

Complete the code to select the least value between three columns 'price1', 'price2', and 'price3'.

MySQL

SELECT LEAST(price1, price2, [1]) AS min_price FROM products;

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

Aprice4

Bprice3

Cprice5

Dprice6

Attempts:

3 left

💡 Hint

Common Mistakes

Using a column not in the table.

Forgetting to include all columns to compare.

The LEAST function returns the smallest value among its arguments. Here, we include 'price3' as the third value.

3fill in blank

hard

Fix the error in the code to correctly find the greatest value between 'value1' and 'value2'.

MySQL

SELECT GREATEST([1], value2) AS highest FROM data;

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

A'value1'

Bvalue_1

CVALUE1

Dvalue1

Attempts:

3 left

💡 Hint

Common Mistakes

Putting column names in quotes.

Using incorrect column names.

Column names should not be in quotes. Use the exact column name 'value1' without quotes.

4fill in blank

hard

Fill both blanks to select the least value between 'temp1' and 'temp2' and alias it as 'lowest_temp'.

MySQL

SELECT LEAST([1], [2]) AS lowest_temp FROM weather;

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

Atemp1

Btemp2

Ctemperature

Dtemp3

Attempts:

3 left

💡 Hint

Common Mistakes

Using columns not in the table.

Swapping the order does not affect the result but use the correct columns.

The LEAST function compares the two columns 'temp1' and 'temp2' to find the smallest value.

5fill in blank

hard

Fill all three blanks to select the greatest value among 'scoreA', 'scoreB', and 'scoreC' and alias it as 'top_score'.

MySQL

SELECT GREATEST([1], [2], [3]) AS top_score FROM exams;

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

AscoreA

BscoreB

CscoreC

DscoreD

Attempts:

3 left

💡 Hint

Common Mistakes

Including columns not in the table.

Missing one of the score columns.

The GREATEST function returns the highest value among the three scores: 'scoreA', 'scoreB', and 'scoreC'.

Practice

1. What does the MySQL function GREATEST(3, 7, 5) return?

easy

A. NULL

B. 3

C. 5

D. 7

Solution

1. Step 1: Understand the GREATEST function

   The GREATEST function returns the largest value among the given arguments.

2. Step 2: Compare the values 3, 7, and 5

   Among 3, 7, and 5, the largest number is 7.

3. Final Answer:

   7 -> Option D

4. Quick Check:

   GREATEST(3, 7, 5) = 7 [OK]

Hint: GREATEST picks the highest number from the list [OK]

Common Mistakes:

• Confusing GREATEST with LEAST
• Thinking it returns the first value
• Assuming it returns a sum

2. Which of the following is the correct syntax to find the smallest value among 10, 20, and 5 using MySQL?

easy

A. MIN(10, 20, 5)

B. LEAST(10, 20, 5)

C. SMALLEST(10, 20, 5)

D. LOWEST(10, 20, 5)

Solution

1. Step 1: Recall the function to find smallest value

   In MySQL, the LEAST function returns the smallest value from a list of arguments.

2. Step 2: Check the syntax options

   LEAST(10, 20, 5) is the correct syntax. MIN is an aggregate function and requires a column, not a list of values. SMALLEST and LOWEST are not valid MySQL functions.

3. Final Answer:

   LEAST(10, 20, 5) -> Option B

4. Quick Check:

   LEAST(10, 20, 5) is correct syntax [OK]

Hint: Use LEAST() for smallest, GREATEST() for largest values [OK]

Common Mistakes:

• Using MIN() with values instead of columns
• Using non-existent functions like SMALLEST()
• Confusing function names

3. Given the table Scores with columns math, science, and english, what will the query SELECT GREATEST(math, science, english) AS top_score FROM Scores WHERE id = 1; return if the row with id = 1 has values (85, 90, 88)?

medium

A. 90

B. 85

C. 88

D. NULL

Solution

1. Step 1: Identify the values for id = 1

   The row has math=85, science=90, english=88.

2. Step 2: Apply GREATEST to these values

   GREATEST(85, 90, 88) returns the largest value, which is 90.

3. Final Answer:

   90 -> Option A

4. Quick Check:

   GREATEST(85, 90, 88) = 90 [OK]

Hint: GREATEST returns the highest among given column values [OK]

Common Mistakes:

• Selecting the first column value instead of greatest
• Confusing GREATEST with LEAST
• Assuming NULL if any value is less

4. Consider this query: SELECT LEAST(score1, score2, score3) FROM Results; It returns NULL for some rows even though all scores are numbers. What is the likely cause?

medium

A. Syntax error in the query

B. LEAST function only works with positive numbers

C. One or more scores are NULL in those rows

D. LEAST returns the largest value, so NULL is unexpected

Solution

1. Step 1: Understand LEAST behavior with NULLs

   LEAST returns NULL if any argument is NULL because NULL means unknown value.

2. Step 2: Check the cause of NULL results

   If some rows have NULL in score1, score2, or score3, LEAST will return NULL for those rows.

3. Final Answer:

   One or more scores are NULL in those rows -> Option C

4. Quick Check:

   LEAST returns NULL if any input is NULL [OK]

Hint: Check for NULLs in inputs; LEAST returns NULL if any argument is NULL [OK]

Common Mistakes:

• Assuming LEAST ignores NULLs
• Thinking LEAST only works with positive numbers
• Misreading LEAST as GREATEST

5. You want to find the highest and lowest scores among three exams for each student in a table Students with columns exam1, exam2, and exam3. Which query correctly returns the student ID, highest score as max_score, and lowest score as min_score?

hard

A. SELECT student_id, GREATEST(exam1, exam2, exam3) AS max_score, LEAST(exam1, exam2, exam3) AS min_score FROM Students;

B. SELECT student_id, MAX(exam1, exam2, exam3) AS max_score, MIN(exam1, exam2, exam3) AS min_score FROM Students;

C. SELECT student_id, GREATEST(exam1, exam2, exam3) AS min_score, LEAST(exam1, exam2, exam3) AS max_score FROM Students;

D. SELECT student_id, MAX(exam1, exam2, exam3) AS min_score, MIN(exam1, exam2, exam3) AS max_score FROM Students;

Solution

1. Step 1: Understand GREATEST and LEAST usage

   GREATEST returns the highest value among columns, LEAST returns the lowest.

2. Step 2: Check the query syntax

   SELECT student_id, GREATEST(exam1, exam2, exam3) AS max_score, LEAST(exam1, exam2, exam3) AS min_score FROM Students; correctly uses GREATEST and LEAST with column names and aliases them properly. MAX and MIN are aggregate functions and cannot take multiple columns as arguments directly.

3. Final Answer:

   Option A query -> Option A

4. Quick Check:

   Use GREATEST and LEAST for column-wise max/min [OK]

Hint: Use GREATEST/LEAST for row-wise max/min, not MAX/MIN [OK]

Common Mistakes:

• Using MAX/MIN with multiple columns incorrectly
• Swapping GREATEST and LEAST aliases
• Syntax errors with aggregate functions