Which of the following is NOT true about a foreign key that connects two tables in a database?

Question

BlackTom AI · Accepted Answer

Question restatement: Which of the following is NOT true about a foreign key that connects two tables in a database?

Option 1: "it must be a primary key in at least one of the tables". This is false because a foreign key in the child table doesn't have to be a primary key anywhere; it must reference a candidate key (often the primary key) in the parent table, but the foreign key column itself need not be a primary key in either table.

Option 2: "it must be of the same data type as the primary key". This is generally true: the foreign key column’s data type should match the referenced primary key’s data type (and size/precision). Mismatched types would impede the integrity check and comparability.

Option 3: "the information being related must be the same as the primary key". Interpreting this as the foreign key value corresponding to a value in the parent table’s primary key is accurate; in a valid relationship, the foreign key must reference an existing primary (or candidate) key value.

Option 4: "it can have null or empty values". This is often permitted if the relationship is optional; a nullable foreign key means the row has no related parent row, which is allowed in many designs.

Option 5: "it must be the same field name as the primary key". This is not required; the foreign key column name on the child table does not need to match the parent table’s primary key column name. They can be named differently and still establish the relationship.

In summary, most textbooks and DBMS documentation emphasize that a foreign key references a candidate key in the parent (typically the primary key), must have a compatible data type, may be nullable if the relationship is optional, and does not have to share the same column name as the primary key. The statement in Option 1 asserts it must be a primary key in at least one table, which mischaracterizes the role of a foreign key and is therefore NOT true. The other options describe typical, valid properties or common allowances of foreign keys.

CSE 2111 AU2025 (10550) Carmen Quiz 9 - Chapter 10 - Database Concepts

Which of the following is NOT true about a foreign key that connects two tables in a database?

View Explanation

Log in for full answers

Similar Questions

If a 1:M relationship is mandatory on both sides, which of the following is true?

Why is a foreign key important in relational databases?

Referential integrity is enforced using:

Which of the following is a characteristic of a foreign key?

A foreign key in one table must refer to:

Which of the following is not a feature of a Foreign Key?

The FOREIGN KEY constraint should be added to which table?

More Practical Tools for International Students

Exam Browser Assistant

Stylized Writing Assistant

Plagiarism Checker Assistant

Citation Assistant

In-Class Translation Assistant

Class Notes Assistant

Quiz Search Assistant

Past Exam Questions by School

Smart Practice Assistant

Adaptive Practice

Making Your Study Simpler