WHERE with AND operator in SQL - Step-by-Step Execution

Concept Flow - WHERE with AND operator

Start Query

↓

Scan Table Rows

↓

Evaluate Condition 1

↓

Evaluate Condition 2

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Condition 1 AND Condition 2?

Yes No↓

Include Row

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Return Filtered Rows

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End

The query scans each row, checks both conditions joined by AND, includes the row only if both are true, then returns all such rows.

Execution Sample

SQL

SELECT * FROM Employees
WHERE Department = 'Sales' AND Salary > 50000;

This query selects employees who work in Sales and earn more than 50000.

Execution Table

Step	Row Data	Condition 1: Department='Sales'	Condition 2: Salary>50000	AND Result	Action
1	{ID:1, Dept:'Sales', Salary:65000}	True	True	True	Include Row
2	{ID:2, Dept:'Sales', Salary:45000}	True	False	False	Skip Row
3	{ID:3, Dept:'HR', Salary:70000}	False	True	False	Skip Row
4	{ID:4, Dept:'Sales', Salary:52000}	True	True	True	Include Row
5	{ID:5, Dept:'IT', Salary:48000}	False	False	False	Skip Row
6	No more rows	-	-	-	End of scan

💡 All rows scanned; only rows where both conditions are true are included.

Variable Tracker

Variable	Start	After Row 1	After Row 2	After Row 3	After Row 4	After Row 5	Final
Current Row	None	{ID:1, Dept:'Sales', Salary:65000}	{ID:2, Dept:'Sales', Salary:45000}	{ID:3, Dept:'HR', Salary:70000}	{ID:4, Dept:'Sales', Salary:52000}	{ID:5, Dept:'IT', Salary:48000}	None
Condition 1 Result	N/A	True	True	False	True	False	N/A
Condition 2 Result	N/A	True	False	True	True	False	N/A
AND Result	N/A	True	False	False	True	False	N/A
Rows Included	[]	[{ID:1,...}]	[{ID:1,...}]	[{ID:1,...}]	[{ID:1,...},{ID:4,...}]	[{ID:1,...},{ID:4,...}]	[{ID:1,...},{ID:4,...}]

Key Moments - 2 Insights

Why is a row skipped even if one condition is true?

Because the AND operator requires both conditions to be true. For example, in step 2, Department='Sales' is true but Salary>50000 is false, so the row is skipped.

What happens if both conditions are false?

The row is skipped since AND needs both true. See step 5 where both conditions are false, so the row is not included.

Visual Quiz - 3 Questions

Look at the execution table, what is the AND result at step 3?

A Unknown

B True

C False

D Error

💡 Hint

Check the 'AND Result' column at step 3 in the execution_table.

At which step does the condition Department='Sales' become false?

A Step 3

B Step 2

C Step 4

D Step 5

💡 Hint

Look at the 'Condition 1' column in the execution_table for false values.

If Salary condition changed to Salary > 60000, which step's AND result would change from True to False?

A Step 1

B Step 4

C Step 5

D Step 2

💡 Hint

Compare Salary values at steps 1 and 4 with new condition >60000.

Concept Snapshot

WHERE clause filters rows based on conditions.
AND operator requires all conditions to be true.
Each row is checked: if all true, row included.
If any condition false, row skipped.
Useful to combine multiple filters in queries.

Full Transcript

This visual execution shows how the SQL WHERE clause with AND operator works. The query scans each row of the Employees table. For each row, it checks if the Department is 'Sales' and if the Salary is greater than 50000. Only rows where both conditions are true are included in the result. The execution table traces each row's data, condition results, and final decision to include or skip. The variable tracker shows how conditions and included rows change step by step. Key moments clarify why rows are skipped if any condition fails. The quiz tests understanding of condition evaluation and AND logic. This helps beginners see exactly how AND filters data in SQL queries.