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List loans with LEFT JOIN

List every member and their loans with LEFT JOIN.

Loaned books

To match loaned books with members you use LEFT JOIN. Books never loaned come as NULL.

SELECT b.title, l.loan_date
FROM books b
LEFT JOIN loans l ON l.book_id = b.id;

This query lists all books with their loan records.

b.title, l.loan_date is selected from books b. loans l is joined on l.book_id = b.id, keeping every row of the left table.

Loaned books — details

LEFT JOIN keeps every book; with no loan record, loan_date becomes NULL.

This way you see every book; a filled loan_date means it is on loan, and NULL means it is on the shelf.

Practice Loaned books

LEFT JOIN all books with the loans table.

Starter code

query.sql
-- loan list
SELECT b.title, l.loan_date
FROM books b

Sample solution

query.sql
SELECT b.title, l.loan_date
FROM books b
LEFT JOIN loans l ON l.book_id = b.id;

Expected output

title     loan_date
Suç ve Ceza  2026-01-10
Sefiller  NULL

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What happens to unloaned books?

  • It is deleted
  • An error
  • They are left out
  • NULL is returned Correct answer

Explanation: LEFT JOIN keeps them with NULL.

2 Add LEFT JOIN

Question 
SELECT b.title, l.loan_date
FROM books b
____ loans l ON l.book_id = b.id;
Answer 
SELECT b.title, l.loan_date
FROM books b
LEFT JOIN loans l ON l.book_id = b.id;

Explanation: LEFT JOIN is the right answer.

3 List loans with LEFT JOIN: match the terms

Term Meaning
books book
loans loan
LEFT JOIN all left
NULL empty

All lessons in Intermediate

1 INNER JOIN in depth

  1. INNER JOIN logic
  2. Choosing the join column
  3. Three-table INNER JOIN
  4. Self JOIN
  5. Filtering joins
  6. Summary - INNER JOIN

2 LEFT and RIGHT JOIN

  1. LEFT JOIN
  2. RIGHT JOIN
  3. Unmatched rows
  4. JOINs with NULL
  5. LEFT vs RIGHT
  6. Summary - LEFT and RIGHT JOIN

3 FULL and CROSS JOIN

  1. FULL OUTER JOIN
  2. CROSS JOIN
  3. When to CROSS JOIN
  4. Comma JOIN
  5. Choosing a JOIN type
  6. Summary - FULL and CROSS JOIN

4 Project: Library database

  1. Library design
  2. Books and authors
  3. List loans with LEFT JOIN
  4. Find overdue loans
  5. Member summary

5 GROUP BY

  1. What is GROUP BY?
  2. Single-column grouping
  3. Multi-column grouping
  4. GROUP BY with aggregates
  5. Ordering grouped results
  6. Summary - GROUP BY

6 HAVING

  1. What is HAVING?
  2. HAVING vs WHERE
  3. HAVING with aggregates
  4. Multiple conditions
  5. HAVING with aliases
  6. Summary - HAVING

7 Aggregate functions

  1. COUNT
  2. SUM
  3. AVG
  4. MIN and MAX
  5. NULL and aggregates
  6. Summary - Aggregates

8 Project: Sales report

  1. Sales design
  2. Daily revenue
  3. Best sellers
  4. Customer segments
  5. Low performers

9 Subquery

  1. What is a subquery?
  2. Scalar subquery
  3. Subquery with IN
  4. ANY and ALL
  5. Correlated subquery
  6. Summary - Subquery

10 EXISTS

  1. What is EXISTS?
  2. NOT EXISTS
  3. EXISTS vs IN
  4. EXISTS performance
  5. Multiple EXISTS
  6. Summary - EXISTS

11 UNION and INTERSECT

  1. UNION
  2. UNION ALL
  3. INTERSECT
  4. EXCEPT
  5. Set rules
  6. Summary - UNION and INTERSECT

12 CASE

  1. What is CASE?
  2. Searched CASE
  3. Simple CASE
  4. The ELSE branch
  5. CASE with aggregates
  6. Summary - CASE

13 VIEW

  1. What is a VIEW?
  2. CREATE VIEW
  3. Querying a VIEW
  4. DROP VIEW
  5. Updatable VIEWs
  6. Summary - VIEW

14 INDEX basics

  1. What is an INDEX?
  2. CREATE INDEX
  3. Composite INDEX
  4. DROP INDEX
  5. When to index
  6. Summary - INDEX

15 Project: Blog database

  1. Blog design
  2. Post list
  3. Tag search
  4. Author stats
  5. Search index

16 Normalization

  1. What is normalization?
  2. First normal form
  3. Second normal form
  4. Third normal form
  5. BCNF
  6. Summary - Normalization

17 Data integrity

  1. What is integrity?
  2. Entity integrity
  3. Referential integrity
  4. Domain integrity
  5. Integrity with triggers
  6. Summary - Data integrity

18 Transaction basics

  1. What is a transaction?
  2. BEGIN and COMMIT
  3. ROLLBACK
  4. SAVEPOINT
  5. ACID
  6. Summary - Transaction

19 ALTER and DROP

  1. ALTER TABLE
  2. Adding a column
  3. Dropping a column
  4. Changing a column type
  5. DROP TABLE
  6. Summary - ALTER and DROP

20 Intermediate final

  1. Multi-JOIN report
  2. Aggregate analysis
  3. Subquery challenge
  4. Transaction scenario