Вземете общи приятели на масата на mysql

Имам User , status и link_user_friend

където потребителят съхранява данни за потребителски детайли статус държи статус на заявка за приятелство link_user_friend държи връзката на потребител и приятел

таблиците са както по-долу

user
+--------+--------+---------+
| fname  | lname  | user_id |
+--------+--------+---------+
| Fone   | Lone!  | ID_1    |
| Ftwo   | Ltwo!  | ID_2    |
| Fthree | Lthree!| ID_3    |
| Ffour  | Lfour! | ID_4    |
| Ffive  | Lfive! | ID_5    |
| Fsix   | Lsix!  | ID_6    |
| Fseven | Lseven!| ID_7    |
| Feight | Leight!| ID_8    |
| Fnine  | Lnine! | ID_9    |
| Ften   | Lten!  | ID_10   |
| Fele   | Lele!  | ID_11   |
| Ftwl   | Ltwl!  | ID_12   |
+---------------------------+

Status        
+-----+-------------------------+
| _id | name                    |
+-----+-------------------------+
|   1 | Friend Request Sent     |
|   2 | Friend Request Rejected |
|   3 | Friends                 |
|   4 | Block                   |
+-----+-------------------------+    

link_user_friend
+-----+---------+------------+--------+
| _id | user_id | friend_id  | status |
+-----+---------+------------+--------+
| a1  | ID_1    | ID_2       |      1 |
| a2  | ID_1    | ID_3       |      2 |
| a3  | ID_1    | ID_4       |      3 |
| a4  | ID_1    | ID_5       |      4 |
| a5  | ID_1    | ID_6       |      3 |
| a6  | ID_1    | ID_7       |      3 |
| a7  | ID_2    | ID_3       |      2 |
| a8  | ID_2    | ID_4       |      1 |
| a9  | ID_2    | ID_5       |      1 |
| b1  | ID_2    | ID_6       |      3 |
| b2  | ID_2    | ID_7       |      2 |
| b3  | ID_2    | ID_8       |      4 |
| b4  | ID_2    | ID_9       |      1 |
| b5  | ID_2    | ID_10      |      2 |
| b6  | ID_2    | ID_11      |      3 |
| b7  | ID_2    | ID_12      |      3 |
| b8  | ID_3    | ID_4       |      3 |
| b9  | ID_3    | ID_5       |      3 |
| c1  | ID_3    | ID_6       |      3 |
| c2  | ID_3    | ID_7       |      3 |
| c3  | ID_3    | ID_8       |      1 |
| c4  | ID_3    | ID_9       |      3 |
| c5  | ID_3    | ID_10      |      3 |
| c6  | ID_3    | ID_11      |      2 |
| c7  | ID_3    | ID_12      |      3 |
| c8  | ID_4    | ID_5       |      3 |
| c9  | ID_4    | ID_6       |      3 |
| d1  | ID_4    | ID_7       |      3 |
| d2  | ID_4    | ID_8       |      3 |
| d3  | ID_4    | ID_9       |      3 |
| d4  | ID_4    | ID_10      |      3 |
| d5  | ID_4    | ID_11      |      3 |
| d6  | ID_4    | ID_12      |      3 |
| d7  | ID_5    | ID_6       |      3 |
| d8  | ID_5    | ID_7       |      3 |
| d9  | ID_5    | ID_8       |      1 |
| e1  | ID_5    | ID_9       |      3 |
| e2  | ID_5    | ID_10      |      3 |
| e3  | ID_5    | ID_11      |      3 |
| e4  | ID_5    | ID_12      |      3 |
| e5  | ID_6    | ID_7       |      3 |
| e6  | ID_6    | ID_8       |      3 |
| e7  | ID_6    | ID_9       |      1 |
| e8  | ID_6    | ID_10      |      3 |
| e9  | ID_6    | ID_11      |      2 |
| f1  | ID_6    | ID_12      |      3 |
| f2  | ID_7    | ID_8       |      3 |
| f3  | ID_7    | ID_9       |      3 |
| f4  | ID_7    | ID_10      |      3 |
| f5  | ID_7    | ID_11      |      3 |
| f6  | ID_7    | ID_12      |      3 |
+-----+---------+------------+--------+

Искам да получа списък с приятели на потребител с общи приятели Засега мога да получа списък с приятели за бивш потребител с идентификатор ID_7

select *
from
((select u.fname fname, u.lname lname, u.user_id, f.status 
from link_user_friend f, user u
where u.user_id = f.friend_id
and f.user_id = 'ID_7'
and f.status = 3)
UNION
(select u.fname, u.lname, u.user_id, f.status 
from link_user_friend f, user u
where u.user_id = f.user_id
and f.friend_id = 'ID_7'
and f.status = 3)) as t order by user_id

ми дава резултат

+--------+---------+---------+--------+
| fname  | lname   | user_id | status |
+--------+---------+---------+--------+
| Fone   | Lone!   | ID_1    |      3 |
| Ften   | Lten!   | ID_10   |      3 |
| Fele   | Lele!   | ID_11   |      3 |
| Ftwl   | Ltwl!   | ID_12   |      3 |
| Fthree | Lthree! | ID_3    |      3 |
| Ffour  | Lfour!  | ID_4    |      3 |
| Ffive  | Lfive!  | ID_5    |      3 |
| Fsix   | Lsix!   | ID_6    |      3 |
| Feight | Leight! | ID_8    |      3 |
| Fnine  | Lnine!  | ID_9    |      3 |
+--------+---------+---------+--------+

по същия начин за

select *
from
((select u.fname fname, u.lname lname, u.user_id, f.status 
from link_user_friend f, user u
where u.user_id = f.friend_id
and f.user_id = 'ID_1'
and f.status = 3)
UNION
(select u.fname, u.lname, u.user_id, f.status 
from link_user_friend f, user u
where u.user_id = f.user_id
and f.friend_id = 'ID_1'
and f.status = 3)) as t order by user_id

Получавам резултат

+--------+---------+---------+--------+
| fname  | lname   | user_id | status |
+--------+---------+---------+--------+
| Ffour  | Lfour!  | ID_4    |      3 |
| Fsix   | Lsix!   | ID_6    |      3 |
| Fseven | Lseven! | ID_7    |      3 |
+--------+---------+---------+--------+

така че когато сравним двете горни таблици, потребителят ID_4, ID_6 са общи приятели на ID_7 и ID_1, така че броят на общите приятели е 2

същото за други потребители, имам нужда от общи приятели, които се броят като още една колона. като

+--------+---------+---------+--------+----------------+
| fname  | lname   | user_id | status | Mutual Friends |
+--------+---------+---------+--------+----------------+
| Fone   | Lone!   | ID_1    |      3 |      2         |
| Ften   | Lten!   | ID_10   |      3 |      .         |
| Fele   | Lele!   | ID_11   |      3 |      .         |
| Ftwl   | Ltwl!   | ID_12   |      3 |      .         |
| Fthree | Lthree! | ID_3    |      3 |      .         |
| Ffour  | Lfour!  | ID_4    |      3 |      .         |
| Ffive  | Lfive!  | ID_5    |      3 |      .         |
| Fsix   | Lsix!   | ID_6    |      3 |      .         |
| Feight | Leight! | ID_8    |      3 |      .         |
| Fnine  | Lnine!  | ID_9    |      3 |      .         |
+--------+---------+---------+--------+----------------+

Не разбирам как да преброя общите приятели. Мислех да повторя всеки запис и да получа общ брой приятели, но има проблем с производителността. Има ли начин да получите само една заявка
Искам списък с общи приятели на произволен потребител, например, ако потребител търси с някакво име. Ще съпоставя това име с потребителската таблица и имам някакъв набор от user_id. за тези user_ids искам общ брой приятели.

Моля, някой може да ми помогне

Прикачих вмъкване и създаване на sql

CREATE TABLE `friend_status` (
  `_id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
  `name` VARCHAR(45) NULL,
  PRIMARY KEY (`_id`));

INSERT INTO `friend_status` (`name`) VALUES ('Friend Request Sent');
INSERT INTO `friend_status` (`name`) VALUES ('Friend Request Rejected');
INSERT INTO `friend_status` (`name`) VALUES ('Friends');
INSERT INTO `friend_status` (`name`) VALUES ('Block');

CREATE TABLE `user` (
  `user_id` VARCHAR(50) NOT NULL,
  `fname` VARCHAR(45) NULL,
  `lname` VARCHAR(45) NULL,
  PRIMARY KEY (`user_id`));

CREATE TABLE `link_user_friend` (
  `_id` VARCHAR(50) NOT NULL,
  `user_id` VARCHAR(50) NOT NULL,
  `friend_id` VARCHAR(50) NOT NULL,
  `status` INT NOT NULL DEFAULT 1,
  PRIMARY KEY (`_id`),
  CONSTRAINT `status`
    FOREIGN KEY (`status`)
    REFERENCES `friend_status` (`_id`)
    ON DELETE CASCADE
    ON UPDATE CASCADE);

Insert into user (`account_type`,`fname`, `lname`, `user_id`) values('1','Ftwo','Ltwo!','ID_2');
Insert into user (`account_type`,`fname`, `lname`, `user_id`) values('1','Fthree','Lthree!','ID_3');
Insert into user (`account_type`,`fname`, `lname`, `user_id`) values('1','Ffour','Lfour! ','ID_4');
Insert into user (`account_type`,`fname`, `lname`, `user_id`) values('1','Ffive','Lfive! ','ID_5');
Insert into user (`account_type`,`fname`, `lname`, `user_id`) values('1','Fsix','Lsix!  ','ID_6');
Insert into user (`account_type`,`fname`, `lname`, `user_id`) values('1','Fseven','Lseven!','ID_7');
Insert into user (`account_type`,`fname`, `lname`, `user_id`) values('1','Feight','Leight!','ID_8');
Insert into user (`account_type`,`fname`, `lname`, `user_id`) values('1','Fnine','Lnine! ','ID_9');
Insert into user (`account_type`,`fname`, `lname`, `user_id`) values('1','Ften','Lten!  ','ID_10');
Insert into user (`account_type`,`fname`, `lname`, `user_id`) values('1','Fele','Lele!  ','ID_11');
Insert into user (`account_type`,`fname`, `lname`, `user_id`) values('1','Ftwl','Ltwl!  ','ID_12');


insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fa1','ID_1','ID_2','1');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fa2','ID_1','ID_3','2');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fa3','ID_1','ID_4','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fa4','ID_1','ID_5','4');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fa5','ID_1','ID_6','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fa6','ID_1','ID_7','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fa7','ID_2','ID_3','2');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fa8','ID_2','ID_4','1');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fa9','ID_2','ID_5','1');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fb1','ID_2','ID_6','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fb2','ID_2','ID_7','2');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fb3','ID_2','ID_8','4');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fb4','ID_2','ID_9','1');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fb5','ID_2','ID_10','2');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fb6','ID_2','ID_11','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fb7','ID_2','ID_12','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fb8','ID_3','ID_4','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fb9','ID_3','ID_5','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fc1','ID_3','ID_6','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fc2','ID_3','ID_7','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fc3','ID_3','ID_8','1');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fc4','ID_3','ID_9','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fc5','ID_3','ID_10','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fc6','ID_3','ID_11','2');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fc7','ID_3','ID_12','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fc8','ID_4','ID_5','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fc9','ID_4','ID_6','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fd1','ID_4','ID_7','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fd2','ID_4','ID_8','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fd3','ID_4','ID_9','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fd4','ID_4','ID_10','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fd5','ID_4','ID_11','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fd6','ID_4','ID_12','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fd7','ID_5','ID_6','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fd8','ID_5','ID_7','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fd9','ID_5','ID_8','1');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fe1','ID_5','ID_9','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fe2','ID_5','ID_10','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fe3','ID_5','ID_11','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fe4','ID_5','ID_12','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fe5','ID_6','ID_7','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fe6','ID_6','ID_8','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fe7','ID_6','ID_9','1');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fe8','ID_6','ID_10','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('fe9','ID_6','ID_11','2');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('ff1','ID_6','ID_12','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('ff2','ID_7','ID_8','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('ff3','ID_7','ID_9','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('ff4','ID_7','ID_10','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('ff5','ID_7','ID_11','3');
insert into link_user_friend (`_id`,`user_id`,`friend_id`,`status`) values('ff6','ID_7','ID_12','3');

mysql join self-join

Sharanabasu Angadi 08.10.2015 източник

comment

моля, добавете извадка от желания резултат - Bernd Buffen 08.10.2015

comment

Моля, добавете също операторите за създаване от вашите таблици, за да видите индекса и типовете данни - Bernd Buffen 08.10.2015

comment

Актуализирах въпроса, моля, проверете, след малко ще добавя изявления за създаване, благодаря - Sharanabasu Angadi 08.10.2015

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Добавих също оператор за създаване, моля, проверете @BerndBuffen - Sharanabasu Angadi 08.10.2015

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За какво е id в таблицата link_user_friend? - Strawberry 08.10.2015

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Благодаря, моля, не ми кажете кои са 3-мата общи приятели от Fone. Няма потребителски ред и не мога да намеря равни потребителски идентификатори. Потребител1 има приятел ID2-7, а Потребител7 има приятел ID8-12 - Bernd Buffen 08.10.2015

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можете да използвате count в oracle и microsoft sql - Stelium 08.10.2015

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@BerndBuffen общи приятели на ID_1 и ID_7, които са потребител 1 и потребител 7 са ID_4 и ID_6, които са общи приятели брой 2 - Sharanabasu Angadi 08.10.2015

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@Sharanabasu Angadi - може ли да поговорим? създадох стая Вземете общи приятели на масата на mysql - Bernd Buffen 08.10.2015

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chat.stackoverflow.com/rooms/91773/ - Bernd Buffen 08.10.2015

Отговори (1)

arrow_upward
1
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За съжаление не можах да се свържа в чата, за да изясня някои неща. Затова написах заявка за вас, която може да направи почти всичко (надявам се). Има 2 реда в края на заявката, където можете да промените функцията й.

първият е редът WHERE u1.user_id ='ID_4' AND u2.user_id ='ID_6'. ако го премахнете, заявката ще изведе всички потребители един към друг или премахнете само втория потребител (u2), получавате списък за всички общи потребители от user1.

второ, можете да премахнете или промените реда HAVING sum_of_mutual_friends > 2, за да промените броя за докладване на потребител

SELECT
  u1.user_id AS user_1,
  u2.user_id AS user_2,
  GROUP_CONCAT(IF( f.user_id = u1.user_id, f.friend_id, f.user_id) SEPARATOR ', ') AS mutual_friends,
  sum(1) sum_of_mutual_friends
FROM USER u1
LEFT JOIN USER u2 ON u1.user_id <> u2.user_id AND u1.user_id < u2.user_id 
LEFT JOIN  link_user_friend f ON f.status =3 AND ( f.user_id = u1.user_id OR f.friend_id = u1.user_id ) AND f.user_id <> u2.user_id
INNER JOIN link_user_friend m ON
  (
    (m.user_id = IF( f.user_id = u1.user_id, f.friend_id, f.user_id)  AND m.friend_id = u2.user_id )
  OR
  (
    m.friend_id = IF( f.user_id = u1.user_id, f.friend_id, f.user_id) AND m.user_id = u2.user_id    )
  )
  AND
    m.status = 3
WHERE u1.user_id ='ID_4' AND u2.user_id ='ID_6'
GROUP BY u1.user_id,u2.user_id
HAVING sum_of_mutual_friends > 2
;

Резултат:

+--------+--------+--------------------------------------------+-----------------------+
| user_1 | user_2 | mutual_friends                             | sum_of_mutual_friends |
+--------+--------+--------------------------------------------+-----------------------+
| ID_4   | ID_6   | ID_1, ID_3, ID_5, ID_7, ID_8, ID_10, ID_12 |                     7 |
+--------+--------+--------------------------------------------+-----------------------+

и без скаде

+--------+--------+---------------------------------------------------------+-----------------------+
| user_1 | user_2 | mutual_friends                                          | sum_of_mutual_friends |
+--------+--------+---------------------------------------------------------+-----------------------+
| ID_1   | ID_10  | ID_4, ID_7, ID_6                                        |                     3 |
| ID_1   | ID_12  | ID_7, ID_6, ID_4                                        |                     3 |
| ID_1   | ID_3   | ID_4, ID_6, ID_7                                        |                     3 |
| ID_1   | ID_5   | ID_7, ID_6, ID_4                                        |                     3 |
| ID_1   | ID_8   | ID_7, ID_6, ID_4                                        |                     3 |
| ID_10  | ID_11  | ID_4, ID_7, ID_5                                        |                     3 |
| ID_10  | ID_12  | ID_5, ID_7, ID_3, ID_4, ID_6                            |                     5 |
| ID_10  | ID_3   | ID_5, ID_6, ID_7, ID_4                                  |                     4 |
| ID_10  | ID_4   | ID_6, ID_7, ID_5, ID_3                                  |                     4 |
| ID_10  | ID_5   | ID_4, ID_7, ID_3, ID_6                                  |                     4 |
| ID_10  | ID_6   | ID_7, ID_5, ID_3, ID_4                                  |                     4 |
| ID_10  | ID_7   | ID_5, ID_4, ID_6, ID_3                                  |                     4 |
| ID_10  | ID_8   | ID_6, ID_4, ID_7                                        |                     3 |
| ID_10  | ID_9   | ID_7, ID_5, ID_4, ID_3                                  |                     4 |
| ID_11  | ID_12  | ID_4, ID_2, ID_5, ID_7                                  |                     4 |
| ID_11  | ID_3   | ID_7, ID_4, ID_5                                        |                     3 |
| ID_11  | ID_6   | ID_7, ID_2, ID_5, ID_4                                  |                     4 |
| ID_11  | ID_9   | ID_7, ID_5, ID_4                                        |                     3 |
| ID_12  | ID_3   | ID_5, ID_6, ID_7, ID_4                                  |                     4 |
| ID_12  | ID_4   | ID_7, ID_5, ID_3, ID_6                                  |                     4 |
| ID_12  | ID_5   | ID_7, ID_3, ID_6, ID_4                                  |                     4 |
| ID_12  | ID_6   | ID_5, ID_4, ID_3, ID_7, ID_2                            |                     5 |
| ID_12  | ID_7   | ID_6, ID_3, ID_5, ID_4                                  |                     4 |
| ID_12  | ID_8   | ID_4, ID_7, ID_6                                        |                     3 |
| ID_12  | ID_9   | ID_5, ID_4, ID_3, ID_7                                  |                     4 |
| ID_2   | ID_4   | ID_11, ID_6, ID_12                                      |                     3 |
| ID_2   | ID_5   | ID_11, ID_6, ID_12                                      |                     3 |
| ID_2   | ID_7   | ID_12, ID_6, ID_11                                      |                     3 |
| ID_3   | ID_4   | ID_6, ID_12, ID_5, ID_9, ID_10, ID_7                    |                     6 |
| ID_3   | ID_5   | ID_7, ID_6, ID_12, ID_9, ID_4, ID_10                    |                     6 |
| ID_3   | ID_6   | ID_12, ID_4, ID_5, ID_10, ID_7                          |                     5 |
| ID_3   | ID_7   | ID_12, ID_6, ID_4, ID_5, ID_10, ID_9                    |                     6 |
| ID_3   | ID_8   | ID_6, ID_7, ID_4                                        |                     3 |
| ID_3   | ID_9   | ID_4, ID_7, ID_5                                        |                     3 |
| ID_4   | ID_5   | ID_9, ID_11, ID_12, ID_7, ID_10, ID_6, ID_3             |                     7 |
| ID_4   | ID_6   | ID_3, ID_1, ID_12, ID_10, ID_7, ID_8, ID_5              |                     7 |
| ID_4   | ID_7   | ID_11, ID_10, ID_9, ID_3, ID_6, ID_12, ID_5, ID_8, ID_1 |                     9 |
| ID_4   | ID_9   | ID_5, ID_7, ID_3                                        |                     3 |
| ID_5   | ID_6   | ID_3, ID_12, ID_4, ID_7, ID_10                          |                     5 |
| ID_5   | ID_7   | ID_6, ID_3, ID_12, ID_4, ID_11, ID_9, ID_10             |                     7 |
| ID_5   | ID_8   | ID_6, ID_4, ID_7                                        |                     3 |
| ID_5   | ID_9   | ID_7, ID_3, ID_4                                        |                     3 |
| ID_6   | ID_7   | ID_3, ID_8, ID_12, ID_5, ID_4, ID_1, ID_10              |                     7 |
| ID_6   | ID_9   | ID_3, ID_4, ID_7, ID_5                                  |                     4 |
| ID_7   | ID_9   | ID_3, ID_4, ID_5                                        |                     3 |
+--------+--------+---------------------------------------------------------+-----------------------+
45 rows in set (0.01 sec)

ЗАБЕЛЕЖКА

трябва да зададете размера на GROUP_CONCAT, ако имате огромни потребителски списъци.

моля, позволете ми сега, ако това е, което търсите.

Bernd Buffen 11.10.2015

comment

това търсех :) .. много ви благодаря :) за запитването, което прави повече от достатъчно... - Sharanabasu Angadi; 11.10.2015

Вземете общи приятели на масата на mysql

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