In SQL, the SELECT statement is commonly used to retrieve data from a database table. One common use case is filtering for NULL values. In this blog post, we will explore how to use the SELECT statement to filter for NULL values in a SQL database.
Let’s say we have a table called employees with the following columns: id, name, and email. We want to retrieve all employees whose email address is NULL.
To perform this task, we can use the IS NULL operator in conjunction with the SELECT statement. Here’s an example query:
SELECT *
FROM employees
WHERE email IS NULL;
In this query, we are selecting all columns from the employees table where the email column is NULL. The IS NULL operator checks if a given value is NULL.
The result of this query will be a list of employees who do not have an email address associated with them.
It’s important to note that the IS NULL operator can only be used with NULL values. If you want to check for non-NULL values, you can use the IS NOT NULL operator instead.
In summary, the SELECT statement in SQL provides a powerful way to filter for NULL values in a database table. By using the IS NULL operator, you can easily retrieve records that have NULL values in a specific column.