I have written the following query to get the value with the max issue_id. But I get the issue_id 14 for book_id 2. What I want is to get issue_id 16 when book_id is 2. And issue_id 15 when book_id is 3 and so on.
SELECT issue.issue_id AS issue_id, issue.issue_date, issue.student_id, books.availability,
CASE WHEN NOW() > DATE_ADD(issue.issue_date, INTERVAL 20 DAY)
THEN 10*DATEDIFF(NOW(), DATE_ADD(issue.issue_date, INTERVAL 20 DAY))
ELSE 0 END AS fine_amount
FROM issue
INNER JOIN books
ON issue.book_id=books.book_id
WHERE books.book_id=2
HAVING MAX(issue.issue_id)
Use the ORDER BY .. LIMIT 1 to get the highest value
SELECT issue.issue_id AS issue_id, issue.issue_date, issue.student_id, books.availability,
CASE WHEN NOW() > DATE_ADD(issue.issue_date, INTERVAL 20 DAY)
THEN 10*DATEDIFF(NOW(), DATE_ADD(issue.issue_date, INTERVAL 20 DAY))
ELSE 0 END AS fine_amount
FROM issue
INNER JOIN books
ON issue.book_id=books.book_id
WHERE books.book_id=2
ORDER BY issue.issue_id DESC LIMIT 1
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