我有User，status和link_user_friend
用户保存用户详细信息的数据
status保存好友请求的状态
link_user_friend拥有用户和朋友的链接
表格如下
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 |
+-----+---------+------------+--------+
我希望与共同的朋友一起获得用户的朋友列表 现在，我可以获得具有Id ID_7
的用户的朋友列表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
给我结果
+--------+---------+---------+--------+
| 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 |
+--------+---------+---------+--------+
的方式相同
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
我得到了结果
+--------+---------+---------+--------+
| fname | lname | user_id | status |
+--------+---------+---------+--------+
| Ffour | Lfour! | ID_4 | 3 |
| Fsix | Lsix! | ID_6 | 3 |
| Fseven | Lseven! | ID_7 | 3 |
+--------+---------+---------+--------+
因此，当我们比较上述两个表时，用户ID_4, ID_6是ID_7和ID_1的常见朋友，因此共有朋友的数量为2
对于其他用户来说，我需要共同的朋友再计算一列。喜欢
+--------+---------+---------+--------+----------------+
| 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 | . |
+--------+---------+---------+--------+----------------+
我不明白如何让共同的朋友们相信。我想迭代每个条目并获得共同的朋友数，但它有性能问题。有没有办法只进入一个查询
我想要任何随机用户的共同朋友列表 例如，如果用户搜索某个名称。我将该名称与用户表匹配，我有一些user_id。对于那些user_ids我想要共同的朋友数。
请有人帮助我
我附加了insert并创建了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');
答案 0 :(得分：1)
不幸的是，为了澄清一些事情，我无法在聊天中联系到。 所以我为你写了一个查询，它可以做几乎所有事情（我希望）。 在查询结尾有一条2行，你可以在其中更改它的功能。
首先是 WHERE u1.user_id =＆＃39; ID_4＆＃39; AND u2.user_id =＆＃39; ID_6＆＃39; 行。如果你删除它，查询将输出所有用户，或者你只删除第二个用户（u2）你从user1获得所有共同用户的列表。
第二，您可以删除或更改 HAVING sum_of_mutual_friends＆gt; 2 行更改计数以报告用户
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
;
结果：
+--------+--------+--------------------------------------------+-----------------------+
| 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 |
+--------+--------+--------------------------------------------+-----------------------+
且没有其中
+--------+--------+---------------------------------------------------------+-----------------------+
| 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)
注意
如果您有庞大的user_lists，则必须设置 GROUP_CONCAT 的大小。
如果您正在寻找的话，请告诉我。