nullväärtus

Nullväärtus, often represented as `null`, is a special marker used in many programming languages and database systems to indicate that a value is intentionally absent or undefined. It signifies the lack of a meaningful data point. This is distinct from a zero (0) or an empty string (""), which are specific values. A null value represents the absence of any value at all.

The interpretation and handling of null values can vary between different programming environments. In some contexts, attempting to perform operations on a null value can lead to errors, such as a null pointer exception. In databases, null values are important for representing missing information, such as a customer's phone number not being provided.

When querying data, it's often necessary to explicitly check for null values to avoid unexpected behavior. Many programming languages provide specific operators or functions to test if a variable or field holds a null value. Understanding null is crucial for writing robust and error-free code, especially when dealing with data that may not always have a complete set of information.