[英]SQL select Distinct with where clause
I have i table like this. 我有这样的表。
PersonID, KvalifikationId
1 1
1 2
1 3
2 1
2 3
I want to write SQL querye returning all persons, that have not kvalifikation 2. 我想编写SQL querye返回所有没有kvalifikation 2的人。
i Wrote 我写
SELECT DISTINCT PersonID where NOT KvalifikationID = 2
But this return both person 1 and person 2. How do i make select that only return personId's that not have kval2 ? 但是这将返回人1和人2.我如何选择只返回没有kval2的personId?
Try this, 试试这个,
SELECT DISTINCT PersonID
FROM tableName
WHERE PersonID NOT IN
(
SELECT PersonID
FROM tableName
WHERE KvalifikationId = 2
)
SELECT DISTINCT person_id
FROM tableName t1
WHERE not exists
(
select 1
from tableName
where person_id = t1.person_id and KvalifikationId = 2
)
Declare @t table(PersonID int,KvalifikationId int)
Insert Into @t Select 1 ,1
Insert Into @t Select 1, 2
Insert Into @t Select 1,3
Insert Into @t Select 2 ,1
Insert Into @t Select 2,3
Select PersonId From @t
Except
Select PersonID From @t where KvalifikationId = 2
Result 结果
PersonId
2
By using your Person
table rather than your N:N table in the outer query you can skip the distinct
and the anti semi join to the sub query will have better performance since it is on a clustered index. 通过在外部查询中使用
Person
表而不是N:N表,可以跳过distinct
,而对于子查询的反半连接将具有更好的性能,因为它在聚簇索引上。 (assuming PersonID
is pk in the Person
table) (假设
PersonID
是Person
表中的pk)
SELECT PersonID
FROM tblPerson
WHERE NOT EXISTS
(
SELECT NULL
FROM tblPersonKvalifikation
WHERE KvalifikationId = 2 AND
tblPerson.PersonID = tblPersonKvalifikation.PersonID
)
try this. 试试这个。
SELECT DISTINCT PersonID from tableName 从tableName中选择DISTINCT PersonID
WHERE KvalifikationId NOT IN ('2'); KvalifikationId不在('2');
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