MySQL IS NOT NULL

The MySQL IS NOT NULL condition is used to check whether a column contains a non-null value. It is often used in the WHERE clause of a SQL query to filter rows where a particular column is not null. The IS NOT NULL condition returns TRUE for rows that have a non-null value in the specified column and FALSE for rows with null values.

The basic syntax of the IS NOT NULL condition is as follows:

SELECT columns
FROM table
WHERE column_name IS NOT NULL;

Here’s how it works:

• column_name is the name of the column you want to check for non-null values.
• If column_name is not null, the condition evaluates to TRUE, and the row is included in the result set.
• If column_name is null, the condition evaluates to FALSE, and the row is excluded from the result set.

Here are some examples to illustrate the use of the IS NOT NULL condition:

1. Match all records where the email column is not null:

   SELECT *
   FROM customers
   WHERE email IS NOT NULL;

2. Retrieve products with a non-null value in the manufacturer column:

   SELECT *
   FROM products
   WHERE manufacturer IS NOT NULL;

3. Find employees with a non-null value in the manager_id column:

   SELECT *
   FROM employees
   WHERE manager_id IS NOT NULL;

The IS NOT NULL condition is a useful tool when you want to filter rows based on the presence or absence of non-null values in a specific column. It is often used in combination with other conditions to build more complex queries.