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Added task 3570#1990

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javadev merged 1 commit intojavadev:mainfromjscrdev:task-3570
Jun 4, 2025
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3570\. Find Books with No Available Copies

Easy

Table: `library_books`

+------------------+---------+
| Column Name | Type |
+------------------+---------+
| book_id | int |
| title | varchar |
| author | varchar |
| genre | varchar |
| publication_year | int |
| total_copies | int |
+------------------+---------+
book_id is the unique identifier for this table.
Each row contains information about a book in the library, including the total number of copies owned by the library.

Table: `borrowing_records`

+---------------+---------+
| Column Name | Type |
|----------------|---------|
| record_id | int |
| book_id | int |
| borrower_name | varchar |
| borrow_date | date |
| return_date | date |
+----------------+---------+
record_id is the unique identifier for this table.
Each row represents a borrowing transaction and return_date is NULL if the book is currently borrowed and hasn't been returned yet.

Write a solution to find **all books** that are **currently borrowed (not returned)** and have **zero copies available** in the library.

* A book is considered **currently borrowed** if there exists a borrowing record with a **NULL** `return_date`

Return _the result table ordered by current borrowers in **descending** order, then by book title in **ascending** order._

The result format is in the following example.

**Example:**

**Input:**

library\_books table:

+---------+--------------------------+----------------+-----------+------------------+--------------+
| book_id | Title | Author | Genre | Publication Year | Total Copies |
|---------|--------------------------|----------------|-----------|------------------|--------------|
| 1 | The Great Gatsby | F. Scott | Fiction | 1925 | 3 |
| 2 | To Kill a Mockingbird | Harper Lee | Fiction | 1960 | 3 |
| 3 | 1984 | George Orwell | Dystopian | 1949 | 1 |
| 4 | Pride and Prejudice | Jane Austen | Romance | 1813 | 2 |
| 5 | The Catcher in the Rye | J.D. Salinger | Fiction | 1951 | 1 |
| 6 | Brave New World | Aldous Huxley | Dystopian | 1932 | 4 |
+---------+--------------------------+----------------+-----------+------------------+--------------+

borrowing\_records table:

+-----------+---------+---------------+-------------+-------------+
| record_id | book_id | borrower_name | borrow_date | return_date |
|-----------|---------|---------------|-------------|-------------|
| 1 | 1 | Alice Smith | 2024-01-15 | NULL |
| 2 | 1 | Bob Johnson | 2024-01-20 | NULL |
| 3 | 2 | Carol White | 2024-01-10 | 2024-01-25 |
| 4 | 3 | David Brown | 2024-02-01 | NULL |
| 5 | 4 | Emma Wilson | 2024-01-05 | NULL |
| 6 | 5 | Frank Davis | 2024-01-18 | 2024-02-10 |
| 7 | 1 | Grace Miller | 2024-02-05 | NULL |
| 8 | 6 | Henry Taylor | 2024-01-12 | NULL |
| 9 | 2 | Ivan Clark | 2024-02-12 | NULL |
| 10 | 2 | Jane Adams | 2024-02-15 | NULL |
+-----------+---------+---------------+-------------+-------------+

**Output:**

+---------+-------------------+----------------+-----------+------------------+-------------------+
| book_id | Title | Author | Genre | Publication Year | Current Borrowers |
|---------|-------------------|----------------|-----------|------------------|-------------------|
| 1 | The Great Gatsby | F. Scott | Fiction | 1925 | 3 |
| 3 | 1984 | George Orwell | Dystopian | 1949 | 1 |
+---------+-------------------+----------------+-----------+------------------+-------------------+

**Explanation:**

* **The Great Gatsby (book\_id = 1):**
* Total copies: 3
* Currently borrowed by Alice Smith, Bob Johnson, and Grace Miller (3 borrowers)
* Available copies: 3 - 3 = 0
* Included because available\_copies = 0
* **1984 (book\_id = 3):**
* Total copies: 1
* Currently borrowed by David Brown (1 borrower)
* Available copies: 1 - 1 = 0
* Included because available\_copies = 0
* **Books not included:**
* To Kill a Mockingbird (book\_id = 2): Total copies = 3, current borrowers = 2, available = 1
* Pride and Prejudice (book\_id = 4): Total copies = 2, current borrowers = 1, available = 1
* The Catcher in the Rye (book\_id = 5): Total copies = 1, current borrowers = 0, available = 1
* Brave New World (book\_id = 6): Total copies = 4, current borrowers = 1, available = 3
* **Result ordering:**
* The Great Gatsby appears first with 3 current borrowers
* 1984 appears second with 1 current borrower

Output table is ordered by current\_borrowers in descending order, then by book\_title in ascending order.
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# Write your MySQL query statement below
# #Easy #Database #2025_06_03_Time_512_ms_(100.00%)_Space_0.0_MB_(100.00%)
SELECT
book_id,
MAX(title) AS title,
MAX(author) AS author,
MAX(genre) AS genre,
MAX(publication_year) AS publication_year,
MAX(total_copies) AS current_borrowers
FROM (
SELECT
book_id,
title,
author,
genre,
publication_year,
total_copies,
total_copies AS total_remain
FROM library_books
UNION ALL
SELECT
book_id,
'' AS title,
'' AS author,
'' AS genre,
1000 AS publication_year,
0 AS total_copies,
-1 AS total_remain
FROM borrowing_records
WHERE return_date IS NULL
) AS sub
GROUP BY
book_id
HAVING
SUM(total_remain) = 0
ORDER BY
current_borrowers DESC,
title ASC;
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package g3501_3600.s3570_find_books_with_no_available_copies;

import static org.hamcrest.CoreMatchers.equalTo;
import static org.hamcrest.MatcherAssert.assertThat;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.stream.Collectors;
import javax.sql.DataSource;
import org.junit.jupiter.api.Test;
import org.zapodot.junit.db.annotations.EmbeddedDatabase;
import org.zapodot.junit.db.annotations.EmbeddedDatabaseTest;
import org.zapodot.junit.db.common.CompatibilityMode;

@EmbeddedDatabaseTest(
compatibilityMode = CompatibilityMode.MySQL,
initialSqls =
"CREATE TABLE library_books(book_id INTEGER, title VARCHAR(255)"
+ ", author VARCHAR(255), genre VARCHAR(255), publication_year "
+ "INTEGER, total_copies INTEGER); "
+ "INSERT INTO library_books (book_id, title, author, genre, "
+ "publication_year, total_copies) VALUES "
+ "(1, 'The Great Gatsby', 'F. Scott', 'Fiction', 1925, 3),"
+ "(2, 'To Kill a Mockingbird', 'Harper Lee', 'Fiction', 1960, 3),"
+ "(3, '1984', 'George Orwell', 'Dystopian', 1949, 1),"
+ "(4, 'Pride and Prejudice', 'Jane Austen', 'Romance', 1813, 2),"
+ "(5, 'The Catcher in the Rye','J.D. Salinger', 'Fiction', 1951, 1),"
+ "(6, 'Brave New World', 'Aldous Huxley', 'Dystopian', 1932, 4);"
+ "CREATE TABLE borrowing_records(record_id INTEGER, book_id INTEGER"
+ ", borrower_name VARCHAR(255), borrow_date DATE, return_date DATE); "
+ "INSERT INTO borrowing_records(record_id, book_id, borrower_name, "
+ "borrow_date, return_date) VALUES "
+ "(1, 1, 'Alice Smith', '2024-01-15', NULL),"
+ "(2, 1, 'Bob Johnson', '2024-01-20', NULL),"
+ "(3, 2, 'Carol White', '2024-01-10', '2024-01-25'),"
+ "(4, 3, 'David Brown', '2024-02-01', NULL),"
+ "(5, 4, 'Emma Wilson', '2024-01-05', NULL),"
+ "(6, 5, 'Frank Davis', '2024-01-18', '2024-02-10'),"
+ "(7, 1, 'Grace Miller', '2024-02-05', NULL),"
+ "(8, 6, 'Henry Taylor', '2024-01-12', NULL),"
+ "(9, 2, 'Ivan Clark', '2024-02-12', NULL),"
+ "(10,2, 'Jane Adams', '2024-02-15', NULL);")
class MysqlTest {
@Test
void testScript(@EmbeddedDatabase DataSource dataSource)
throws SQLException, FileNotFoundException {
try (final Connection connection = dataSource.getConnection()) {
try (final Statement statement = connection.createStatement();
final ResultSet resultSet =
statement.executeQuery(
new BufferedReader(
new FileReader(
"src/main/java/g3501_3600/"
+ "s3570_find_books_with_no_available_copies/"
+ "script.sql"))
.lines()
.collect(Collectors.joining("\n"))
.replaceAll("#.*?\\r?\\n", ""))) {
assertThat(resultSet.next(), equalTo(true));
assertThat(resultSet.getNString(1), equalTo("1"));
assertThat(resultSet.getNString(2), equalTo("The Great Gatsby"));
assertThat(resultSet.getNString(3), equalTo("F. Scott"));
assertThat(resultSet.getNString(4), equalTo("Fiction"));
assertThat(resultSet.getNString(5), equalTo("1925"));
assertThat(resultSet.getNString(6), equalTo("3"));
assertThat(resultSet.next(), equalTo(true));
assertThat(resultSet.getNString(1), equalTo("3"));
assertThat(resultSet.getNString(2), equalTo("1984"));
assertThat(resultSet.getNString(3), equalTo("George Orwell"));
assertThat(resultSet.getNString(4), equalTo("Dystopian"));
assertThat(resultSet.getNString(5), equalTo("1949"));
assertThat(resultSet.getNString(6), equalTo("1"));
assertThat(resultSet.next(), equalTo(false));
}
}
}
}
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