mysql

 Question:

The following query results in 2,698 rows of data being retrieved, but the auditor_report table only has 1,620 rows.
Analyse the query and select the reason why this discrepancy occurs.

 Answer:

The discrepancy occurs because the query uses a JOIN (most likely an INNER JOIN or LEFT JOIN) that matches multiple rows from another table for each record in auditor_report.

When a join condition is not unique — for example, if the joined table has duplicate matching keys — the result set will multiply rows.
Each matching combination between the two tables will create a new row in the output, leading to more rows than exist in the base table.

 Example:

SELECT a.*, b.*
FROM auditor_report a
JOIN auditor_details b ON a.report_id = b.report_id;

If:

• auditor_report has 1,620 rows,

• auditor_details has multiple rows for each report_id,

then the result may expand to 2,698 rows or more, depending on how many matches exist per report.

 In short:

The query returns more rows than the auditor_report table because of a one-to-many relationship in the join, causing row duplication.

 Tip:

To verify, you can run:

SELECT report_id, COUNT(*) 
FROM auditor_details 
GROUP BY report_id 
HAVING COUNT(*) > 1;

This will show which report_ids cause duplicates in the join.