Find overdue loans
- SQL course
- Intermediate
- Lesson 22/115
- 5 min
Find overdue loans with LEFT JOIN and WHERE.
Overdue books
To find overdue books you filter the LEFT JOIN result with WHERE. Records past their due date are picked.
SELECT b.title, l.due_date
FROM books b
LEFT JOIN loans l ON l.book_id = b.id
WHERE l.due_date < CURRENT_DATE;This query returns books past their due date.
b.title, l.due_date is selected from books b. loans l is joined on l.book_id = b.id, keeping every row of the left table. WHERE keeps only the rows where l.due_date < CURRENT_DATE holds.
Overdue books — details
CURRENT_DATE gives today. If due_date is earlier, the book is overdue.
This query lists loans whose due date is before today; ORDER BY due_date puts the most overdue book at the top.
Practice Overdue books
Filter the LEFT JOIN result with due_date < CURRENT_DATE.
Starter code
-- overdue
SELECT b.title, l.due_date
FROM books b
LEFT JOIN loans l ON l.book_id = b.idSample solution
SELECT b.title, l.due_date
FROM books b
LEFT JOIN loans l ON l.book_id = b.id
WHERE l.due_date < CURRENT_DATE;Expected output
title due_date Suç ve Ceza 2026-01-10
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Find overdue loans: match the terms
| Term | Meaning |
|---|---|
CURRENT_DATE |
today |
due_date |
due date |
WHERE |
filter |
overdue |
past due |
2 How is overdue detected?
- When due_date is earlier than today Correct answer
- When due_date is later
- With SUM
- With COUNT
Explanation: due_date < CURRENT_DATE signals overdue.
3 Add WHERE
SELECT b.title, l.due_date
FROM books b
LEFT JOIN loans l ON l.book_id = b.id
____ l.due_date < CURRENT_DATE;SELECT b.title, l.due_date
FROM books b
LEFT JOIN loans l ON l.book_id = b.id
WHERE l.due_date < CURRENT_DATE;Explanation: WHERE l.due_date < CURRENT_DATE finds loans whose due date has passed.