Why WHERE with IS NULL and IS NOT NULL in SQL? - Purpose & Use Cases

The Big Idea

What if you could instantly find all missing pieces in your data without endless searching?

The Scenario

Imagine you have a big list of customer orders on paper. Some orders have missing delivery dates, but you want to find only those missing dates or only those that have dates filled in. Doing this by scanning each paper manually is tiring and slow.

The Problem

Manually checking each order for missing or present dates is error-prone and takes a lot of time. You might miss some or mix them up, especially if the list is very long.

The Solution

Using WHERE IS NULL and WHERE IS NOT NULL in SQL lets you quickly and accurately find rows with missing or present values. This saves time and avoids mistakes.

Before vs After

✗ Before

Check each row one by one for missing values.

✓ After

SELECT * FROM orders WHERE delivery_date IS NULL;
SELECT * FROM orders WHERE delivery_date IS NOT NULL;

What It Enables

This lets you instantly filter data based on whether information is missing or available, making data handling smarter and faster.

Real Life Example

A store manager wants to see all orders that haven't been shipped yet (missing shipping date) to follow up quickly.

Key Takeaways

Manually finding missing data is slow and error-prone.

IS NULL and IS NOT NULL help filter missing or present values easily.

This makes data queries faster and more reliable.