In database programming, which of the following are typical capabilities of a cursor when processing query results?

Introduction / Context:
In relational database systems, a cursor is a database object that allows an application or stored procedure to process query results row by row. While set based operations are preferred for performance, cursors are useful when each row requires special handling that is difficult to express in a single SQL statement. Understanding what a cursor can do, including iterating through rows, using parameters, and positioning within a result set, is important for database developers and administrators.

Given Data / Assumptions:

• We are working with relational databases that support cursors, such as Oracle, SQL Server, or PostgreSQL.
• A cursor is associated with the result set of a SELECT statement.
• The application or procedure can fetch one row at a time using the cursor.
• Cursors may support additional features such as parameters and scrollable positioning.

Concept / Approach:
A basic cursor reads rows one by one, which is its most fundamental capability. Many implementations also support parameterised cursors, where the underlying query contains parameters that can be passed at runtime, making the cursor reusable for different input values. Some cursor types are scrollable, meaning they can move not only forward but also backward or jump to specific rows based on relative or absolute positions. When a question lists these abilities, the correct answer is often that all described capabilities are supported by cursors in general, even though exact support depends on the database engine and cursor type.

Step-by-Step Solution:
Step 1: Recognise that reading rows one by one is a core use of cursors, allowing procedural logic to handle each row individually.Step 2: Understand that many relational databases support parameterised cursors or cursor variables, making them flexible for different input conditions.Step 3: Recall that some cursor types, such as scrollable or insensitive cursors, support positioning operations like moving to the next, previous, first, or last row.Step 4: Evaluate each statement in the options and see that options A, B, and C all refer to valid cursor capabilities.Step 5: Conclude that option D, which states All of the above, correctly summarises the combined capabilities.

Verification / Alternative check:
In practice, you can verify these capabilities by writing a stored procedure that declares a cursor for a SELECT query. Use FETCH NEXT to read successive rows, demonstrating option A. Modify the cursor definition to include parameters, such as a department identifier, and pass different values when opening the cursor, which demonstrates option B. Finally, declare a scrollable cursor and use FETCH PRIOR, FETCH FIRST, or FETCH LAST to move to specific positions in the result set, demonstrating option C. This experiment confirms that cursors can read one row at a time, be parameterised, and be positioned on specific rows.

Why Other Options Are Wrong:
Each of options A, B, and C correctly describes a cursor capability, so none of them alone captures the full picture. The question asks which capabilities are provided, and because all three statements are valid, the best answer is the combined choice All of the above in option D. There is no separate option suggesting that some of these capabilities are invalid, so recognising that all three are correct is essential.

Common Pitfalls:
A common pitfall is to assume that cursors are always scrollable, when in many systems basic cursors can only move forward. Developers must choose the correct cursor type if they need random access. Another pitfall is overusing cursors where set based SQL would be more efficient, leading to performance issues. Cursors are powerful but should be used carefully, with attention to transaction scope and resource usage. Understanding their capabilities and limitations helps developers select the right tool for each data processing task.

Final Answer:
Correct answer: All of the above