Concat into a single row different values of a duplicated ID - mysql

Question

I'm developing a application for library management.
The problem is, I have the following tables: user, employee, loan, book_loan, with them I need a query that returns me an unique
loan's ID, with the user's name, employee's name, book's name, loan's date, devolution's date and status.
I almost did this, but it returns me duplicates of the loan's ID, with the book's name separated by the rows.
These are my tables:
delimiter $$
CREATE TABLE `Loan` (
`id_loan` int(11) NOT NULL AUTO_INCREMENT,
`id_user` int(11) NOT NULL,
`id_employee` int(11) NOT NULL,
`date_loan` date NOT NULL,
`data_devolution` date NOT NULL,
`status` tinyint(1) NOT NULL DEFAULT '1',
PRIMARY KEY (`id_loan`),
KEY `fk_loan_id_user_idx` (`id_user`),
KEY `fk_loan_id_employee` (`id_employee`),
CONSTRAINT `fk_loan_id_employee` FOREIGN KEY (`id_emplyee`) REFERENCES `Employee` (`id_employee`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `fk_loan_id_user` FOREIGN KEY (`id_user`) REFERENCES `User` (`id_user`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=33 DEFAULT CHARSET=utf8$$
delimiter $$
CREATE TABLE `Employee` (
`id_employee` int(11) NOT NULL AUTO_INCREMENT,
`login` varchar(20) NOT NULL,
`password` varchar(16) NOT NULL,
`level` decimal(10,0) NOT NULL,
PRIMARY KEY (`id_employee`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8$$
delimiter $$
CREATE TABLE `Book` (
`id_book` int(11) NOT NULL AUTO_INCREMENT,
`title` varchar(50) NOT NULL,
`id_author` int(11) NOT NULL,
`edition` decimal(10,0) NOT NULL,
`editor` varchar(45) NOT NULL,
`cutter` varchar(12) NOT NULL,
`id_CDU` int(11) NOT NULL,
`status` tinyint(1) NOT NULL DEFAULT '1',
PRIMARY KEY (`id_book`),
KEY `fk_book_id_CDU_idx` (`id_CDU`),
KEY `fk_book_id_author` (`id_author`),
CONSTRAINT `fk_book_id_author` FOREIGN KEY (`id_author`) REFERENCES `Author` (`id_author`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `fk_book_id_CDU` FOREIGN KEY (`id_CDU`) REFERENCES `CDU` (`id_CDU`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8$$
delimiter $$
CREATE TABLE `Book_Loan` (
`id_book` int(11) NOT NULL,
`id_loan` int(11) NOT NULL,
KEY `fk_book_loan_id_loan` (`id_loan`),
KEY `fk_book_loan_id_book` (`id_book`),
CONSTRAINT `fk_book_loan_id_loan` FOREIGN KEY (`id_loan`) REFERENCES `Loan` (`id_loan`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `fk_book_loan_id_book` FOREIGN KEY (`id_book`) REFERENCES `Book` (`id_book`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=utf8$$
delimiter $$
CREATE TABLE `User` (
`id_user` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(50) NOT NULL,
`address` varchar(50) NOT NULL,
`email` varchar(50) NOT NULL,
PRIMARY KEY (`id_user`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8$$
This is my query:
SELECT loan.id_loan AS ID,
employee.login AS EMPLOYEE,
user.name AS USER,
book.title AS BOOK,
loan.date_loan AS LOAN,
loan.date_devolution AS DEVOLUTION,
loan.status AS STATUS
FROM Loan loan
INNER JOIN Employee employee ON employee.id_employee = loan.id_employee
INNER JOIN User user ON user.id_user = loan.id_user
INNER JOIN Book_Loan book_loan ON book_loan.id_loan = loan.id_loan
INNER JOIN Book book ON book.id_book = book_loan.id_book;
That returns me e.g.: if the loan has 3 book, which is the maximum:
+-----+-------------+-------------+---------------------------------+------------+------------+--------+
| ID | EMPLOYEE | USER | BOOK | LOAN | DEVOLUTION| STATUS |
+-----+-------------+-------------+---------------------------------+------------+------------+--------+
| 6 | RUBE | John | Book A | 2013-06-22 | 2013-06-29 | 0 |
| 6 | RUBE | John | Book B | 2013-06-22 | 2013-06-29 | 0 |
| 6 | RUBE | John | Book C | 2013-06-22 | 2013-06-29 | 0 |
+-----+-------------+-------------+---------------------------------+------------+------------+--------+
This is what I want:
+-----+-------------+-------------+---------------------------------+------------+------------+--------+
| ID | EMPLOYEE | USER | BOOK | LOAN | DEVOLUTION | STATUS |
+-----+-------------+-------------+---------------------------------+------------+------------+--------+
| 6 | RUBE | John | Book A, Book B, Book C | 2013-06-22 | 2013-06-29 | 0 |
+-----+-------------+-------------+---------------------------------+------------+------------+--------+

Answer 1

Look into using GROUP_CONCAT:
SELECT loan.id_loan AS ID,
employee.login AS EMPLOYEE,
user.name AS USER,
GROUP_CONCAT(book.title) AS BOOK,
loan.date_loan AS LOAN,
loan.date_devolution AS DEVOLUTION,
loan.status AS STATUS
FROM Loan loan
INNER JOIN Employee employee ON employee.id_employee = loan.id_employee
INNER JOIN User user ON user.id_user = loan.id_user
INNER JOIN Book_Loan book_loan ON book_loan.id_loan = loan.id_loan
INNER JOIN Book book ON book.id_book = book_loan.id_book
GROUP BY loan.id_loan