Description: Entity constraint is a fundamental rule in database design that defines the valid values for the attributes of an entity. This constraint ensures that the data stored in a database is consistent and meets certain predefined conditions. For example, in a database, an entity constraint might specify that the ‘age’ field must be an integer within a given range, such as between 18 and 65. Entity constraints are crucial for maintaining data integrity, as they prevent the entry of incorrect or inappropriate information. Additionally, these constraints can include conditions such as uniqueness, where certain attributes, like an identification number, must be unique for each record. In summary, entity constraints are essential for ensuring that the data in a database is valid, coherent, and useful for subsequent queries and analyses.
