find_in_set with join in laravel - laravel

Question

How to get the desire output using laravel query. Tried that way does not get success please guide thanks a lot in advance
Is there any way we can set it in model if possible please guide
User
id name b_id
1 Alax 1,3
2 Rex 2,4
3 Lex 2,3
Books
id book_name book_author
1 Javascript jim
2 PHP json
3 LARAVEL rax
4 SYMPHONY Alax
Output
id name b_id
1 Alax Javascript, LARAVEL
2 Rex PHP, SYMPHONY
3 Lex PHP, LARAVEL
And Query:
$res = DB::table('user')->leftJoin('book', function($join){
$join->on(DB::raw("find_in_set(book.id, user.b_id)",DB::raw(''),DB::raw('')));
});

Answer 1

Try this.
$data = \DB::table("user")
->select("user.*",\DB::raw("GROUP_CONCAT(book.book_name) as book_name"))
->leftjoin("book",\DB::raw("FIND_IN_SET(book.id,user.b_id)"),">",\DB::raw("'0'"))
->get();
\DB::raw("GROUP_CONCAT(CONCAT(book.book_name, ' - ', book.book_author) SEPARATOR ', ') AS book_name_author")
Your output looks like.
Illuminate\Support\Collection Object
(
[items:protected] => Array
(
[0] => stdClass Object
(
[id] => 1
[name] => Alax
[b_id] => 1,3
[book_name] => Javascript,LARAVEL
)
[1] => stdClass Object
(
[id] => 2
[name] => Rex
[b_id] => 2,4
[book_name] => PHP,SYMPHONY
)
[2] => stdClass Object
(
[id] => 3
[name] => Lex
[b_id] => 2,3
[book_name] => PHP,LARAVEL
)
)
)

Answer 2

I don't know the exact Laravel syntax problem you are currently facing, but there is a potential problem with your current left join logic. If a given user have more than one matching book, then he would appear in the result set one time for each match. This presumably is not what you want, so I would suggest joining using EXISTS logic:
SELECT u.id, u.name
FROM User u
WHERE EXISTS (SELECT 1 FROM Books b WHERE FIND_IN_SET(b.id, u.b_id) > 0);
The Laravel code:
$res = DB::table('user u')
->whereExists(function ($query) {
$query->select(DB::raw(1))
->from('book b')
->whereRaw('FIND_IN_SET(b.id, u.b_id) > 0');
})
->get();
The exists approach ensures that each user would only appear once in the result set.