Entity Integrity Basics Quiz

Entity integrity is a fundamental principle in relational databases that mandates each table row must have a unique primary key. This ensures that every record can be distinctly identified, and the primary key cannot contain null values, reinforcing the reliability and consistency of the data within the database.

A primary key serves as a unique identifier for each record in a database table. To fulfill this role, it must ensure that no two rows have the same key value and that every row has a key assigned, thus preventing any null entries. This guarantees data integrity and efficient retrieval.

A primary key uniquely identifies each record in a database table. To maintain this uniqueness, a primary key cannot contain null values, as nulls indicate the absence of a value and would prevent the identification of a specific record. Thus, every entry in a primary key must be defined and unique.

Student ID is the most appropriate primary key because it uniquely identifies each student in the table, ensuring that no two records can have the same value. Unlike Student Name, Major, or GPA, which can be duplicated or changed, Student ID remains constant and distinct for each individual, making it ideal for primary key usage.

A table can only have one primary key, which uniquely identifies each record. While a primary key can consist of multiple columns (composite key), it is still considered a single key. Having multiple primary keys would create ambiguity in record identification, violating the principles of relational database design.

A composite primary key is a unique identifier for a database record that consists of two or more columns. This combination ensures that each record can be uniquely identified, which is particularly useful in situations where a single column is insufficient to guarantee uniqueness.

A unique constraint ensures that all values in a column are distinct, but it permits null values. This means that while no two non-null values can be the same, multiple rows can have null values, unlike a primary key, which cannot allow any nulls at all.

Entity integrity ensures that each entity in a database has a unique identifier, typically a primary key. This enforcement occurs at the database engine level, where the underlying database management system maintains rules and constraints to guarantee that no two records can have the same key value, thus preserving data accuracy and reliability.

Entity integrity is a fundamental principle in relational databases that mandates each row in a table must be unique, typically enforced through primary keys. This ensures that no two rows can be identical, maintaining the accuracy and reliability of the data within the table.

A PRIMARY KEY constraint uniquely identifies each record in a database table, ensuring that no two rows can have the same value in the specified column(s). This enforces entity integrity by preventing duplicate entries and ensuring that every record can be uniquely identified, which is essential for maintaining accurate and reliable data.

When a database encounters an attempt to insert a row with a duplicate primary key value, it enforces data integrity rules. Since primary keys must be unique to identify each record distinctly, the database will reject the operation to prevent data conflicts and maintain the integrity of the dataset.

Entity integrity is a fundamental principle in relational databases that ensures each row in a table is uniquely identifiable. Violations occur when a primary key, which must be unique and not null, is duplicated or left empty. This undermines the integrity of the database by allowing ambiguity in record identification.