MySQL Query Review

Problem Statement

The question asked to write a MySQL query that retrieves the user_id and a formatted name from the Activity table. The formatted name should have its first letter in uppercase and the remaining letters in lowercase. The query provided was:

SELECT 
 user_id,
 CONCAT(UPPER(SUBSTR(name, 1, 1)), LOWER(SUBSTR(name, 2))) AS name
FROM Activity
ORDER BY 1 ASC;

Issue Identification

The problem was that the ORDER BY 1 ASC clause uses a column ordinal (the number 1) to indicate that the results should be sorted by the first column in the SELECT list. While this is often acceptable in many MySQL environments, some SQL environments or strict SQL modes may disallow the use of ordinal numbers for sorting, which can cause a runtime error.

Resolution

To resolve the error, replace the numeric column reference with the actual column name in the ORDER BY clause. This ensures clarity and avoids any potential ambiguity or restrictions in the SQL environment.

Updated Query

SELECT 
 user_id,
 CONCAT(UPPER(SUBSTR(name, 1, 1)), LOWER(SUBSTR(name, 2))) AS name
FROM Activity
ORDER BY user_id ASC;

By explicitly specifying user_id in the ORDER BY clause, the query becomes clear and compliant with environments that do not support ordinal ordering.

Summary

• Original Query Issue: Using ORDER BY 1 ASC can cause runtime errors in environments that do not allow ordinal references.
• Solution: Replace ORDER BY 1 ASC with ORDER BY user_id ASC.
• Final Query: The updated query retrieves the user data and formats the name correctly while sorting the results by user_id.