查询到两个记录之间找到差异

Question

我有如下表

movies 
    - id 

details 
    - user_id 
    - movie_id 
    - rating 

users 
    - id 

细节属于用户和电影

我想找到两个用户的等级之间的差异的说ID 3,10

只是我想这

sum(10-(user1.rating - user2.rating)) 
    where rating is > 0 

答案即两个用户应该在，至少不给泽RO评级

Answer 1

select 
d1.movie_id 
, d1.rating as user1Rating 
, d2.rating as user2Rating 
, abs(d1.rating - d2.rating) 
from 
details d1 
inner join details d2 on d1.movie_id = d2.movie_id 
where d1.user_id = 1 
and d2.user_id = 2 

See it working live in an sqlfiddle.

Answer 2

DECLARE @UserRating1 int 
DECLARE @UserRating2 int 
DECLARE @UserID1 int 
DECLARE @UserID2 int 
DECLARE @MovieID int 

SET @MovieID = 99 
SET @UserID1 = 3 
SET @UserID2 = 10 

SET @UserRating1 = (SELECT Rating FROM details WHERE movie_id = @MovieID AND user_id = @UserID1 AND Rating > 0) 
SET @UserRating2 = (SELECT Rating FROM details WHERE movie_id = @MovieID AND user_id = @UserID2 AND Rating > 0) 

PRINT @UserRating1 - @UserRating2 

Answer 3

CREATE TABLE ratings 
( userId int, movieId int, rating int) 

INSERT INTO ratings (userId, movieId, rating) VALUES 
    (3, 1, 5), (10, 1, 8), 
    (3, 2, 10), (10, 2, 3) 

SELECT r1.movieId, (r1.rating - r2.rating) FROM ratings as r1 
INNER JOIN ratings as r2 on r1.movieId = r2.movieId 
WHERE r1.userId = 3 and r2.userId = 10 

Answer 4

更新：我代替从MSSQL语法到MySql

您可以SQL Fiddle检查：

create table movies (id int); 
insert into movies (id) values (1); 
insert into movies (id) values (2); 
insert into movies (id) values (3); 
insert into movies (id) values (4); 
insert into movies (id) values (5); 

create table users (id int); 
insert into users (id) values (1); 
insert into users (id) values (2); 
insert into users (id) values (3); 
insert into users (id) values (4); 
insert into users (id) values (5); 
insert into users (id) values (10); 

create table details (user_id int, movie_id int, rating int); 

insert into details (user_id, movie_id, rating) values (3,1,1); 
insert into details (user_id, movie_id, rating) values (3,2,2); 
insert into details (user_id, movie_id, rating) values (3,3,3); 
insert into details (user_id, movie_id, rating) values (3,4,1); 
insert into details (user_id, movie_id, rating) values (3,5,4); 

insert into details (user_id, movie_id, rating) values (10,1,3); 
insert into details (user_id, movie_id, rating) values (10,2,1); 
insert into details (user_id, movie_id, rating) values (10,3,2); 
insert into details (user_id, movie_id, rating) values (10,4,1); 
insert into details (user_id, movie_id, rating) values (10,5,5); 

和

select 
    sum(10-(details1.rating - details2.rating)) 
from 
    movies 
    inner join details details1 on movies.id = details1.movie_id 
    inner join users user1 on details1.user_id = user1.id 
    inner join details details2 on movies.id = details2.movie_id 
    inner join users user2 on details2.user_id = user2.id 
where 
    (user1.id=3) 
    and 
    (user2.id=10) 
    and 
    (details1.rating is not null) and (details1.rating > 0) 
    and 
    (details2.rating is not null) and (details2.rating > 0)