In relational database systems, which of the following best describes the original purpose for which the Structured Query Language SQL was designed?

Introduction / Context:
This question focuses on the history and core purpose of the Structured Query Language SQL in relational database management systems. Understanding why SQL was created helps learners appreciate its major components such as data definition, data manipulation, and data control. It also clarifies why SQL became a standard language across many relational database products from different vendors.

Given Data / Assumptions:

- The question asks for the original purpose of SQL.- SQL is tightly associated with relational databases.- Several options describe different possible uses such as structure definition, manipulation, or unrelated tasks.

Concept / Approach:
SQL was originally developed by IBM under the name SEQUEL as a high level language to interact with relational databases based on the relational model. Its key goals were to provide a standardized way to define database structures, query and update data, and control access. In modern terms, this corresponds to the data definition language DDL, data manipulation language DML, and data control language DCL aspects of SQL. The correct choice must therefore reflect a broad and comprehensive purpose, not a narrow or unrelated task.

Step-by-Step Solution:
Step 1: Evaluate option A, which limits SQL to defining table structures only. This describes only DDL and ignores querying or updating data.Step 2: Evaluate option B, which mentions non relational file systems. SQL was not designed primarily for non relational files but for relational databases.Step 3: Evaluate option C, which states that SQL provides a standard language for defining, manipulating, and controlling data in relational databases. This matches DDL, DML, and DCL.Step 4: Consider option D, which talks about designing networks. That is outside the scope of SQL.Step 5: Consider option E, which relates to user interface layouts. Again, this is not an SQL responsibility.Step 6: Conclude that option C accurately captures the original purpose of SQL.

Verification / Alternative check:
Standard database textbooks describe SQL as a comprehensive language for defining, querying, and controlling relational data. Database product documentation from vendors such as Oracle, Microsoft, and open source platforms confirms that SQL is divided into DDL, DML, and DCL components. None of these sources describe SQL as a network design tool or graphical interface design language, which confirms that the broad, relational focus in option C is correct.

Why Other Options Are Wrong:
Option A is incomplete because it ignores querying and updating data, which are central to SQL. Option B is incorrect because SQL was not created for non relational file systems. Option D is unrelated since computer network design involves protocols and hardware, not SQL. Option E is also unrelated because graphical user interface design is handled by other technologies, not by SQL statements.

Common Pitfalls:
Learners sometimes focus on the part of SQL they use most often, such as SELECT queries, and forget that SQL also defines tables, constraints, and security. Others may confuse SQL with general programming or scripting languages used in application development. It is important to remember that SQL is specifically oriented toward relational data and is standardized to allow similar syntax across different databases.

Final Answer:
The original purpose of SQL was to provide a standard language for defining, manipulating, and controlling data in relational databases.