GREATEST and LEAST in MySQL - Step-by-Step Execution

Concept Flow - GREATEST and LEAST

Start with values

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Compare values pairwise

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GREATEST: Select largest value

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LEAST: Select smallest value

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Return result

GREATEST compares values and returns the largest; LEAST returns the smallest among given values.

Execution Sample

MySQL

SELECT GREATEST(3, 7, 5) AS max_val, LEAST(3, 7, 5) AS min_val;

This query finds the largest and smallest values among 3, 7, and 5.

Execution Table

Step	Values Compared	GREATEST Result	LEAST Result	Explanation
1	3 and 7	7	3	Compare first two values: 7 is greater, 3 is smaller
2	7 and 5	7	3	Compare previous greatest 7 with 5: 7 remains greatest; least stays 3
3	All values compared	7	3	Final greatest is 7, least is 3

💡 All values compared, final greatest and least values returned

Variable Tracker

Variable	Start	After 1	After 2	Final
GREATEST	N/A	7	7	7
LEAST	N/A	3	3	3

Key Moments - 2 Insights

Why does GREATEST return 7 and not 5 or 3?

Because in the execution_table rows 1 and 2, 7 is compared with other values and remains the largest.

Why does LEAST return 3 and not 5 or 7?

Because 3 is the smallest value found after comparing all values as shown in execution_table rows 1 and 2.

Visual Quiz - 3 Questions

Look at the execution_table, what is the GREATEST result after step 1?

A 5

B 3

C 7

D None

💡 Hint

Check the 'GREATEST Result' column in execution_table row 1

At which step does the LEAST value become final?

A Step 1

B Step 3

C Step 2

D Never

💡 Hint

Look at the 'LEAST Result' column and the exit_note in execution_table

If we change the values to (10, 2, 8), what would GREATEST return?

A 10

B 8

C 2

D None

💡 Hint

GREATEST returns the largest value among the inputs, similar to the tracked variable in variable_tracker

Concept Snapshot

GREATEST(value1, value2, ...) returns the largest value.
LEAST(value1, value2, ...) returns the smallest value.
They compare all given values pairwise.
Useful for quick max/min among multiple values.
NULL input returns NULL if any value is NULL.

Full Transcript

This visual execution trace shows how MySQL functions GREATEST and LEAST work by comparing multiple values step-by-step. Starting with the values 3, 7, and 5, the functions compare pairs to find the largest and smallest values. After comparing 3 and 7, 7 is the greatest and 3 the least. Then 7 is compared with 5, and 7 remains greatest while 3 remains least. Finally, the functions return 7 as the greatest and 3 as the least. This helps beginners see how these functions pick the max and min values from a list.