MySQL IFNULL() Function

 The IFNULL() function in MySQL is used to return a specified value if the expression is NULL. If the expression is not NULL, it returns the expression's value. It is commonly used for handling NULL values in queries, making sure the output is more user-friendly by replacing NULL with a specified value.

Syntax:

IFNULL(expression, alternative_value)

• expression: The value or column to check for NULL.
• alternative_value: The value that will be returned if the expression is NULL.

Example:

1. Basic usage:

   SELECT IFNULL(column_name, 'Default Value') FROM table_name;
   

   If column_name contains NULL, it will return 'Default Value'; otherwise, it returns the value of column_name.

2. Using with arithmetic:

   SELECT IFNULL(price, 0) AS price_with_default FROM products;
   

   If price is NULL, it will return 0; otherwise, it will return the actual price.

3. Replacing NULL with another value:

   SELECT IFNULL(name, 'No Name') FROM employees;
   

   This will return 'No Name' for records where the name column is NULL.

Notes:

• IFNULL() works well for dealing with NULL values in query results and can help ensure that your applications or reports don't encounter errors or unexpected behavior when handling NULL.
• It's similar to the COALESCE() function but with a slight difference in behavior. COALESCE() can take multiple arguments and returns the first non-NULL value, while IFNULL() only takes two arguments.