BETWEEN for range filtering in PostgreSQL - Step-by-Step Execution

Concept Flow - BETWEEN for range filtering

Start Query

↓

Check BETWEEN condition

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Include row

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Return filtered rows

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End

The query checks each row to see if a value falls within a range using BETWEEN. Rows that satisfy the condition are included in the result.

Execution Sample

PostgreSQL

SELECT * FROM products WHERE price BETWEEN 10 AND 20;

This query selects all products with prices from 10 to 20 inclusive.

Execution Table

Step	Row ID	price	Condition: price BETWEEN 10 AND 20	Include Row?
1	1	5	5 BETWEEN 10 AND 20? FALSE	No
2	2	10	10 BETWEEN 10 AND 20? TRUE	Yes
3	3	15	15 BETWEEN 10 AND 20? TRUE	Yes
4	4	20	20 BETWEEN 10 AND 20? TRUE	Yes
5	5	25	25 BETWEEN 10 AND 20? FALSE	No
6	End			Query ends, all rows checked

💡 All rows checked; rows with price between 10 and 20 inclusive are included.

Variable Tracker

Variable	Start	After Row 1	After Row 2	After Row 3	After Row 4	After Row 5	Final
price	N/A	5	10	15	20	25	N/A
Include Row?	N/A	No	Yes	Yes	Yes	No	N/A

Key Moments - 3 Insights

Does BETWEEN include the boundary values?

Yes, as shown in execution_table rows 2 and 4, prices exactly 10 and 20 are included because BETWEEN is inclusive.

What happens if the value is less than the lower bound?

As in row 1, price 5 is less than 10, so the condition is false and the row is excluded.

Is BETWEEN equivalent to using >= and <=?

Yes, price BETWEEN 10 AND 20 is the same as price >= 10 AND price <= 20, including boundaries.

Visual Quiz - 3 Questions

Look at the execution_table, what is the Include Row? value for Row ID 3?

A No

B Maybe

C Yes

D Not checked

💡 Hint

Check the row with Row ID 3 in the execution_table under Include Row? column.

At which step does the condition first become TRUE?

A Step 1

B Step 2

C Step 5

D Step 6

💡 Hint

Look at the Condition column in execution_table to find the first TRUE.

If the BETWEEN range changed to 15 AND 25, which row would now be included that was previously excluded?

A Row ID 5

B Row ID 2

C Row ID 1

D Row ID 3

💡 Hint

Check the price values and see which row's price falls between 15 and 25 but was excluded before.

Concept Snapshot

BETWEEN syntax: value BETWEEN low AND high
Includes values from low to high, inclusive.
Equivalent to value >= low AND value <= high.
Used for filtering rows within a range.
Easy way to check if a value falls inside a range.

Full Transcript

This visual execution shows how the SQL BETWEEN operator filters rows by checking if a value lies within a specified range. Each row's price is tested against the condition price BETWEEN 10 AND 20. Rows with prices 10, 15, and 20 satisfy the condition and are included in the result. Rows with prices outside this range are excluded. BETWEEN includes the boundary values, making it equivalent to using >= and <= together. This step-by-step trace helps beginners see how each row is evaluated and understand the inclusive nature of BETWEEN.