Added task 3570

src/main/java/g3501_3600/s3570_find_books_with_no_available_copies/readme.md

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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.

src/main/java/g3501_3600/s3570_find_books_with_no_available_copies/script.sql

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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;

src/test/java/g3501_3600/s3570_find_books_with_no_available_copies/MysqlTest.java

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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));
+            }
+        }
+    }
+}