In DB2, what condition does the SQLCODE -811 error indicate when executing a SELECT with an INTO clause?

Introduction / Context:
SQLCODE values are a fundamental part of DB2 error handling. Developers must recognize common codes quickly to diagnose problems. SQLCODE -811 is frequently seen when a query that is expected to return a single row actually returns multiple rows. This question checks whether the candidate remembers that specific meaning and can distinguish it from other error conditions such as not found or syntax problems.

Given Data / Assumptions:

• We are executing a SELECT statement that uses INTO to put column values into a single row target, such as host variables.
• The WHERE clause was intended to identify a unique row in the table.
• DB2 returns SQLCODE -811 during execution.

Concept / Approach:
When a SELECT with an INTO clause is coded, DB2 expects the query to produce either one row or no rows. If the query returns no rows, codes such as +100 may be returned, indicating not found. If the query returns more than one row, DB2 cannot decide which one set of values should be placed into the INTO variables, so it raises SQLCODE -811. The correct option must mention this multiple row situation, not unrelated issues like locking or syntax errors.

Step-by-Step Solution:
Step 1: Recognize that SELECT INTO is designed for single row retrieval in embedded SQL. Step 2: Recall the meaning of common SQLCODE values: +100 for no data found, -811 for more than one row returned into a single row context. Step 3: Understand that when the WHERE clause is not selective enough, more than one row may qualify. Step 4: DB2 detects this and aborts the operation with SQLCODE -811 because it cannot map multiple rows into a single set of host variables. Step 5: Therefore, identify the correct option as the one that states that multiple rows were returned where only one was expected.

Verification / Alternative check:
You can verify by rewriting the same SELECT without the INTO clause and running it in an interactive DB2 session. If you see more than one row in the result set, that confirms the cause of SQLCODE -811. If instead there are no rows, SQLCODE +100 would be expected, and if there were other issues like syntax errors, DB2 would raise a different code during compilation rather than execution.

Why Other Options Are Wrong:
Option B is wrong because an empty result set yields a not found condition, not SQLCODE -811.
Option C is wrong because locking conflicts yield timeouts or deadlock codes, not the multiple row SQLCODE -811.
Option D is wrong because syntax errors are detected during statement preparation or bind and lead to different negative SQLCODE values.

Common Pitfalls:
Developers sometimes forget to enforce uniqueness in WHERE clauses and are surprised by -811 at runtime. Another pitfall is ignoring error handling and assuming that SELECT INTO will always succeed. Proper coding should check SQLCODE after execution and handle -811 by revisiting the query or adjusting the data model, for example by enforcing a unique key. It is also important not to confuse -811 with other negative codes that indicate different failure modes.

Final Answer:
SQLCODE -811 means that the SELECT statement returned more than one row into a single row target, causing a multiple row result error.