Relational database model: which of the following is NOT a characteristic feature? Identify the option that does not align with how relational databases are structured and related.

Introduction / Context:
Relational databases organize data into tables (relations) consisting of rows (tuples) and columns (attributes). Relationships are defined via keys and constraints rather than by fixed pointer structures. This question targets differentiating the relational model from hierarchical or network models.

Given Data / Assumptions:

• Relational model uses tables, rows, and columns.
• Relationships are expressed through keys, joins, and constraints.
• “Treelike structure” is typical of hierarchical databases.

Concept / Approach:
A treelike structure implies parent–child pointers and a strict hierarchy, which is the hallmark of hierarchical DBMSs. Relational systems avoid hardwired physical navigation; instead, they rely on logical relationships evaluated at query time using joins and predicates. They certainly can represent complex logical relationships (one-to-many, many-to-many via junction tables) without embedding a tree.

Step-by-Step Solution:
List relational features: tables, rows (records), keys, constraints.Compare to options; “treelike structure” does not belong.Confirm others: tables and records are intrinsic; complex logical relationships are supported via joins and constraints.

Verification / Alternative check:
SQL queries (SELECT with JOIN) illustrate logical relationships independent of physical layout; ER modeling maps naturally onto relational schemas without enforcing a tree navigation path.

Why Other Options Are Wrong:

• Tables / records: Core relational constructs.
• Complex logical relationships: Achieved via foreign keys, junction tables, and constraints.
• None of the above: Incorrect because one option is clearly non-relational.

Common Pitfalls:
Equating directory trees or XML hierarchies with relational schemas; assuming that “record” is not used in relational contexts—rows are often informally called records.

Final Answer:
treelike structure