What does "Null Values" mean?

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Null values are used in programming and databases to represent missing or unknown information. When a piece of data is expected but not present, it is often marked as null. This can happen for various reasons, like when a user does not provide input or when data is still being gathered.

In many programming languages, having a null value can lead to problems. For example, if a program tries to perform an operation on a null value, it may cause an error. This is why some languages have rules to handle null values carefully.

Null values can appear in databases as well. When working with tables of information, a null value indicates that there is no data in that cell. For example, if you have a table of customers and one customer did not provide a phone number, that field would be null.

Dealing with null values requires special attention to avoid mistakes in calculations or data retrieval. Some systems use specific methods to handle these nulls correctly, ensuring that users receive accurate results even when some information is missing.