Sql 仅当“相关实体”列包含特定值时才选择

我很难理解sql查询。 我想选择所有只拥有名称包含“Test”的许可证的公司

因此，在示例中，Microsoft有2个许可证。一次测试和一次商业测试 所以我不想要那家公司。 但是所有苹果的许可证都是测试许可证，所以我想选择苹果

我想的是：

SELECT Company.Name, COUNT(Company.Name) 
FROM Company INNER JOIN  License ON License.CompanyId = Company.pkId
WHERE License.Name LIKE '%Test%'
GROUP BY Company.Name

获取每个公司包含“Test”的行数，并将其与

SELECT Company.Name, COUNT(Company.Name) 
FROM Company INNER JOIN  License ON License.CompanyId = Company.pkId
GROUP BY Company.Name

如果数量上没有差异，我有一家公司只有测试许可证。

---

但是我不知道如何将它们全部合并，或者是否有更好的方法。

您想要的是从另一个集合中减去一个集合（即返回一个集合，但不在另一个集合中显示行），这就是（在Oracle中为负）操作符所做的。此查询应提供您想要的内容：

SELECT c.pkId, c.Name FROM Company c
INNER JOIN License l ON c.pkId=l.CompanyId
WHERE l.Name LIKE '%Test%'
EXCEPT
SELECT c.pkId, c.Name FROM Company c
INNER JOIN License l ON c.pkId=l.CompanyId
WHERE l.Name NOT LIKE '%Test%'

还有其他方法可以做到这一点，但这应该是最直接的方法

---

.

如果是SQL Server数据库，则这是一次尝试：-

declare @company table (pkid int, name varchar(20))

insert into @company values (1,'microsoft')
insert into @company values (2,'apple')

declare @license table (pkid int, companyid int, name varchar(20))

insert into @license values (1,1,'license test')
insert into @license values (2,1,'comm')
insert into @license values (3,2,'license test')
insert into @license values (4,2,'license test')

select * from @company
select * from @license

select c.name
from @license l
inner join @company c
on c.pkid = l.companyid
where l.companyid not in
(select companyid from @license l1
where l1.name not like '%test%')
group by c.name

---

如果所有公司都至少有一个许可证，则以下操作将起作用。它检查是否有不用于“测试”的许可证：

但是，我认为我更喜欢使用

exists

和

notexists

子句：

select c.*
from company c
where exists (select 1
              from License l
              where l.CompanyId = c.pkId and l.Name LIKE '%Test%'
             ) and
      not exists (select 1
                  from License l
                  where l.CompanyId = c.pkId and l.Name not LIKE '%Test%'
                 );

这表示至少存在一行带有“test”，而没有一行没有

或者，您可以将其表述为聚合查询中的

having

子句：

select c.Name 
from Company c inner join
     License l
     ON l.CompanyId = c.pkId
group by c.Name
having sum(case when l.Name like '%Test%' then 1 else 0 end) > 0 and
       sum(case when l.Name not like '%Test%' then 1 else 0 end) = 0;

---

我复制了您的示例，第一个查询的结果是（2,1），第二个查询的结果是（2,2）

SELECT COUNT(License.Name) AS counter, Company.Name
FROM Company INNER JOIN License ON License.CompanyId = Company.pkId
WHERE License.Name LIKE '%Test%'
GROUP BY Company.Name
HAVING counter = (SELECT MAX(counted) FROM (SELECT COUNT(l.Name) AS counted FROM License AS l WHERE l.name LIKE '%Test%' GROUP BY l.companyid) AS co)

---

当询问数据库相关问题时，您应该始终指定您正在使用的特定数据库系统；能力和解决方案各不相同。你说得对。现在编辑，谢谢！按照我希望的方式工作。第一个查询似乎返回相反的结果（它得到了Microsoft，但没有苹果的示例数据）。@jpw。真奇怪。不知怎么的，我只是没有完成那个查询。现在是

与
where
的
左连接，因此应该可以工作。
select c.Name 
from Company c inner join
     License l
     ON l.CompanyId = c.pkId
group by c.Name
having sum(case when l.Name like '%Test%' then 1 else 0 end) > 0 and
       sum(case when l.Name not like '%Test%' then 1 else 0 end) = 0;

SELECT COUNT(License.Name) AS counter, Company.Name
FROM Company INNER JOIN License ON License.CompanyId = Company.pkId
WHERE License.Name LIKE '%Test%'
GROUP BY Company.Name
HAVING counter = (SELECT MAX(counted) FROM (SELECT COUNT(l.Name) AS counted FROM License AS l WHERE l.name LIKE '%Test%' GROUP BY l.companyid) AS co)