IF function in MySQL - Step-by-Step Execution

Concept Flow - IF function

Evaluate condition

Yes↓

Return value_if_true

↓

END

No↓

Return value_if_false

↓

END

The IF function checks a condition. If true, it returns one value; if false, it returns another.

Execution Sample

MySQL

SELECT IF(5 > 3, 'Yes', 'No') AS result;

This query returns 'Yes' because 5 is greater than 3.

Execution Table

Step	Condition	Condition Result	Value if True	Value if False	Returned Value
1	5 > 3	True	'Yes'	'No'	'Yes'
2	3 > 5	False	'Yes'	'No'	'No'
3	10 = 10	True	'Equal'	'Not Equal'	'Equal'
4	7 < 2	False	'Less'	'More or Equal'	'More or Equal'
Exit	No more conditions	-	-	-	Execution ends

💡 All conditions evaluated; IF function returns corresponding values and ends.

Variable Tracker

Variable	Start	After 1	After 2	After 3	After 4	Final
Condition	-	True	False	True	False	-
Returned Value	-	'Yes'	'No'	'Equal'	'More or Equal'	-

Key Moments - 2 Insights

Why does IF(3 > 5, 'Yes', 'No') return 'No' instead of 'Yes'?

Because the condition 3 > 5 is false, so IF returns the value_if_false, which is 'No' as shown in execution_table row 2.

What happens if the condition is true?

IF returns the value_if_true immediately, as in execution_table rows 1 and 3 where conditions are true and the first value is returned.

Visual Quiz - 3 Questions

Look at the execution_table row 1. What is the returned value when condition 5 > 3 is evaluated?

A 'Maybe'

B 'Yes'

C 'No'

D '5 > 3'

💡 Hint

Check the 'Returned Value' column in row 1 of the execution_table.

At which step does the IF function return 'No'?

A Step 2

B Step 1

C Step 3

D Step 4

💡 Hint

Look for 'No' in the 'Returned Value' column in the execution_table.

If the condition was changed to 7 > 2 in step 4, what would be the returned value?

A 'True'

B 'Less'

C 'More or Equal'

D '7 > 2'

💡 Hint

Refer to the 'Value if False' column in step 4 of the execution_table.

Concept Snapshot

IF(condition, value_if_true, value_if_false)
Checks condition; returns value_if_true if true, else value_if_false.
Used in SELECT to choose values based on logic.
Condition must be a boolean expression.
Returns exactly one of the two values.

Full Transcript

The IF function in MySQL evaluates a condition. If the condition is true, it returns the first value. If false, it returns the second value. For example, IF(5 > 3, 'Yes', 'No') returns 'Yes' because 5 is greater than 3. Each step in the execution table shows the condition checked and the value returned. Beginners often wonder why IF returns the second value; it is because the condition was false. Changing the condition changes which value is returned. This function helps make decisions inside queries.