Practice mode DBMS and SQL

Which data model organises records in a tree, so that each child record has exactly one parent record?

Correct answer A. Hierarchical model

Explanation

The hierarchical model arranges records as a tree of parent-child links, so a child can have only one parent, which makes many-to-many relationships awkward. The network model relaxes this by allowing a record to have several owners, forming a graph. The relational model avoids explicit links altogether and represents relationships through matching values in tables, and the ER model is mainly a design tool.

Report a problem

Answer checked 12 October 2026 How we write and check questions

Tip: press A, B, C or D to answer, and N for the next question.

Which data model organises records in a tree, so that each child record has exactly one parent record?

Discussion

Have a question about this answer? Cancel reply

Which data model organises records in a tree, so that each child record has exactly one parent record?

More DBMS and SQL questions

Table Emp(id, dept, salary) has rows (1,’HR’,3000), (2,’IT’,5000), (3,’IT’,4000), (4,’HR’,NULL), (5,’Ops’,2000). SELECT COUNT(*), COUNT(salary) FROM Emp; What does this query return?

Table Emp(id, dept, salary) has rows (1,’HR’,3000), (2,’IT’,5000), (3,’IT’,4000), (4,’HR’,NULL), (5,’Ops’,2000). SELECT AVG(salary) FROM Emp WHERE dept = ‘HR’; What value is returned?

Table Emp(id, dept, salary) has rows (1,’HR’,3000), (2,’IT’,5000), (3,’IT’,4000), (4,’HR’,NULL), (5,’Ops’,2000). SELECT dept, SUM(salary) FROM Emp GROUP BY dept HAVING SUM(salary) > 3000 ORDER BY dept; Which rows are returned?

Table Emp(id, dept, salary) has rows (1,’HR’,3000), (2,’IT’,5000), (3,’IT’,4000), (4,’HR’,NULL), (5,’Ops’,2000). SELECT COUNT(DISTINCT dept) FROM Emp; What is the output?

Discussion

Have a question about this answer? Cancel reply