重复查询

Question

有人可以帮我解决这个问题：

我有数据，客户有多条记录（在一张表中，这是一个读入表格的平面文件），例如。

Name  Policy
Fred  SSS
Fred  SST
Joe   SSS

我需要提取政策=＆＃39; SSS＆＃39;但是那个客户只有一个SSS＆＃39;政策。所以只有Joe会从上面返回

Answer 1

select name
from yourtable
group by name
having count(policy)=1 and max(policy)='SSS'

Answer 2

SELECT Name
FROM tableName a
WHERE Policy = 'SSS'
GROUP BY Name
HAVING COUNT(*) = (SELECT COUNT(*) FROM tableName b WHERE a.Name = b.Name)

SQLFiddle Demo