Find overdue loans

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.

Exercise Overdue books

Filter the LEFT JOIN result with due_date < CURRENT_DATE.

Show example 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;

Test yourself

Find overdue loans: match the terms

CURRENT_DATE

today
due_date

due date
WHERE

filter
overdue

past due
How is overdue detected?
- When due_date is earlier than today
- When due_date is later
- With SUM
- With COUNT
Show answer

When due_date is earlier than today — due_date < CURRENT_DATE signals overdue.

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;

Show answer

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;

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