Description: A value constraint is a rule that restricts the values that can be stored in a column of a database. These constraints are fundamental for maintaining data integrity, ensuring that only valid and consistent values are entered. For example, in a database that stores information about employees, a value constraint can be set on the age column to only accept integer values between 18 and 65. Value constraints can be of different types, such as data type constraints, which limit values to a specific type (like integers or text strings), or range constraints, which specify an acceptable range of values. Additionally, these constraints can be implemented at the column level or at the table level, depending on the database structure. Implementing value constraints not only helps prevent errors in data entry but also facilitates the validation and analysis of the stored information, thus contributing to the quality and reliability of data in database management systems.
