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A field with a NULL value is a field with no value. If a field in a table is optional, it is possible to insert a new record or update a record without adding a value to this field. Then, the field will be saved with a NULL value. Note:A NULL value is different from a zero value or a field that contains spaces.
17 mar 2021 · Question: What is an SQL NULL? NULLs represent absent or unknown values; they are used for fields with unknown or inapplicable values. NULLs should not be confused with zeros or spaces. They must be handled carefully in SQL queries, as NULLs can impact query results in unexpected ways.
20 cze 2024 · This tip will help you understand what NULL means in the context of the Microsoft Fabric data universe, which includes SQL Server. It will then show how these values can make queries act unexpectedly and how to best interact with NULL values to avoid problems.
NULL in SQL represents missing or unknown values. It is not zero, not an empty string, or not any other default value. It’s simply a representation of ‘no data’. It’s important to understand that a NULL value isn’t equivalent to anything else, not even another NULL value.
19 maj 2021 · What is a SQL NULL value? In terms of the relational database model, a NULL value indicates an unknown value. If we widen this theoretical explanation, the NULL value points to an unknown value but this unknown value does not equivalent to a zero value or a field that contains spaces.
In SQL, null is a marker, not a value. This usage is quite different from most programming languages, where a null value of a reference means it is not pointing to any object.
2 mar 2012 · A value of NULL indicates the value is unknown. A value of NULL is different from an empty or zero value. No two null values are equal. Comparisons between two null values, or between a NULL and any other value, return unknown because the value of each NULL is unknown.
