这个MySQL in子句中的负值有什么问题？

Question

我有一个这样的观点：

TABLE_TYPE
(code,name)
(1,'Computer')
(2,'Television')
(3,'Radio')

TABLE_THING
(code,name,type=TABLE_TYPE:code)
(-9999, 'ThingFirst',1)
(1,'Thing1',1)
(2,'Thing2',2)
(3,'Thing3',2)
(4,'Thing4',3)
(5,'Thing5',1)

VIEW_THINGS
(code,name,thingtype)
(-9999, 'ThingFirst','Computer')
(1,'Thing1','Computer')
(2,'Thing2','Television')
(3,'Thing3','Television')
(4,'Thing4','Radio')
(5,'Thing5','Computer')

查询：

select * from VIEW_THINGS where code in (-9999,1,2,3,4,5)

结果是：

(-9999, 'ThingFirst',NULL)

结果应该是：

(-9999, 'ThingFirst','Computer')
(1,'Thing1','Computer')
(2,'Thing2','Television')
(3,'Thing3','Television')
(4,'Thing4','Radio')
(5,'Thing5','Computer')

怎么了？

Tip1:当我退出IN子句中的负值(-9999)时，我得到的结果是：

(1,'Thing1','Computer')
(2,'Thing2','Television')
(3,'Thing3','Television')
(4,'Thing4','Radio')
(5,'Thing5','Computer')

Tip2:如果我从总视图结果中选择，我会得到正确的数据：

select * from (select * from VIEW_THINGS as T) where code in (-9999,1,2,3,4,5)

结果：

(-9999, 'ThingFirst','Computer')
(1,'Thing1','Computer')
(2,'Thing2','Television')
(3,'Thing3','Television')
(4,'Thing4','Radio')
(5,'Thing5','Computer')

Answer 1

完整的测试脚本：

create table TABLE_TYPE(code int,name varchar(20));
insert table_type values
(1,'Computer'),
(2,'Television'),
(3,'Radio');

create table TABLE_THING(code int,name varchar(20),type int);
insert table_thing values
(-9999, 'ThingFirst',1),
(1,'Thing1',1),
(2,'Thing2',2),
(3,'Thing3',2),
(4,'Thing4',3),
(5,'Thing5',1);

create table VIEW_THINGS(code int, name varchar(20),thingtype varchar(20));
insert view_things values
(-9999, 'ThingFirst','Computer'),
(1,'Thing1','Computer'),
(2,'Thing2','Television'),
(3,'Thing3','Television'),
(4,'Thing4','Radio'),
(5,'Thing5','Computer');

select * from VIEW_THINGS where code in (-9999,1,2,3,4,5);

输出

"code";"name";"thingtype"
"-9999";"ThingFirst";"Computer"
"1";"Thing1";"Computer"
"2";"Thing2";"Television"
"3";"Thing3";"Television"
"4";"Thing4";"Radio"
"5";"Thing5";"Computer"

由于这是可行的，所以我敢打赌，VIEW_THINGS是一个连接两个表的视图。让我们看看

create view view_things2
as
select t.code, t.name, y.name thingtype
from table_thing t
inner join table_type y on y.code = t.type
;
select * from VIEW_THINGS2 where code in (-9999,1,2,3,4,5);

输出:如上所述

这是我们对您提供的信息所能做的最大努力。

Answer 2

你有没有尝试过改变顺序，比如

SELECT * FROM VIEW_THINGS WHERE code IN (1,2,3,4,5,-9999)