这个 MySQL IN 子句中的负值有什么问题？

Question

我有这样的看法：

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？？？？

提示1：当我从 IN 子句中退出负值 (-9999) 时，我会得到：

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

提示2：如果我从总视图结果中进行选择，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"

既然这样有效，我会说 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

这是我们所能提供的信息。

Answer 2

你尝试过改变订单吗

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