sql - 从具有多行的表中选择某些 ID，并带有标识符值

Question

我目前有以下结果：

ID    Location
1     NYC
1     LA
2     NYC
3     PIT

我想要以下内容：

ID    Location
1     Multiple
2     NYC
3     PIT

有谁知道一个简单的方法来完成这个？

Answer 1

这是使用 and 的case一种count方法distinct：

select distinct id, 
  case when count(location) over (partition by id ) > 1 
    then 'Multiple' else location end Location
from yourtable

• SQL 小提琴演示

Answer 2

sub-query, COUNT, CASE, GROUP BY: _

SELECT mm.id, CASE WHEN mm.count > 1 THEN 'Multiple' ELSE loc END As Location
FROM
(SELECT COUNT(id) As count, id, MAX(location) As loc
FROM myTable
GROUP BY id) As mm;

SQL小提琴

Answer 3

select ID,case when MIN(name) = MAX(name) then  MIN(name) else 'multiple' end as Location
from <your tabel name>
group by id