NOT NULL

Description: The ‘NOT NULL’ constraint in databases is a directive applied to the columns of a table, ensuring that null values cannot be stored in them. This means that each row in the table must contain a valid value in that column, which is crucial for maintaining data integrity. Implementing this constraint is fundamental in database design, as it allows developers and administrators to ensure that certain fields, which are essential for business logic, always contain information. For example, in a user table, it is likely that the email field should not accept null values, as it is a key identifier for communication. The ‘NOT NULL’ constraint is defined when creating or modifying a table, and failing to comply will result in an error when trying to insert or update records. This feature helps prevent errors in data manipulation and improves the quality of the stored information, facilitating more accurate and effective queries.

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