MIN and MAX functions in SQL - Step-by-Step Execution

Concept Flow - MIN and MAX functions

Start with a column of values

↓

Apply MIN function

→Find smallest value

↓

Apply MAX function

→Find largest value

↓

Return result as single value

MIN finds the smallest value in a column, MAX finds the largest, both return one value.

Execution Sample

SQL

SELECT MIN(age) AS Youngest, MAX(age) AS Oldest FROM people;

This query finds the youngest and oldest ages from the people table.

Execution Table

Step	Action	Column Values	MIN Result	MAX Result
1	Read all ages	[23, 45, 31, 19, 40]
2	Find minimum age	[23, 45, 31, 19, 40]	19
3	Find maximum age	[23, 45, 31, 19, 40]	19	45
4	Return results		19	45

💡 All values processed, MIN and MAX results returned

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
ages	[23, 45, 31, 19, 40]	[23, 45, 31, 19, 40]	[23, 45, 31, 19, 40]	[23, 45, 31, 19, 40]
min_age	NULL	19	19	19
max_age	NULL	NULL	45	45

Key Moments - 2 Insights

Why does MIN return only one value even though there are many ages?

MIN scans all values but returns only the smallest one as a single result, as shown in execution_table step 2.

Can MIN and MAX be used on text columns?

Yes, MIN returns the alphabetically first value and MAX the last, similar to numeric values but based on sorting order.

Visual Quiz - 3 Questions

Look at the execution table, what is the MIN result after step 2?

A 23

B 45

C 19

D NULL

💡 Hint

Check the 'MIN Result' column at step 2 in the execution_table.

At which step does the MAX function find the largest value?

A Step 2

B Step 3

C Step 1

D Step 4

💡 Hint

Look at the 'MAX Result' column in the execution_table to see when MAX is assigned.

If the ages were all the same, what would MIN and MAX return?

A The same value

B NULL

C Different values

D Error

💡 Hint

MIN and MAX return the smallest and largest values respectively; if all values are equal, both return that value.

Concept Snapshot

MIN(column) returns the smallest value in a column.
MAX(column) returns the largest value.
Both return a single value.
Used to find extremes in data.
Works on numbers and text (alphabetical order).

Full Transcript

The MIN and MAX functions in SQL help find the smallest and largest values in a column. For example, given ages 23, 45, 31, 19, and 40, MIN returns 19 and MAX returns 45. The process reads all values, finds the minimum and maximum, then returns these as single results. These functions work on numbers and text, returning the smallest or largest based on sorting. They always return one value, even if many rows exist.