选择计数和聚合，但只能是唯一的

Question

我有一个数据库（MSSQL），其表格如下：

CREATE TABLE [dbo].[Ciphers](
    [Time] [datetime] NULL,
    [Hostname] [varchar](50) NULL,
    [ClientIP] [varchar](50) NULL,
    [UserAgent] [varchar](550) NULL,
    [CipherName] [varchar](200) NULL,
    [CipherVersion] [varchar](100) NULL,
    [CipherBits] [varchar](50) NULL
) ON [PRIMARY]

几行可能如下所示：

现在我想计算每个顶级域名的CipherName，CipherVersion和CipherBits组合的出现次数。

几乎是这样的：

SELECT CipherName, CipherVersion, CipherBits, COUNT(ClientIP) As "Hits" 
from Ciphers
WHERE Hostname like '%domain.com' 
Group by CipherName, CipherVersion, CipherBits 

关键是我只想计算每个客户端IP的唯一实例。也就是说，如果客户浏览过sub.domain.com和test.domain.com，我不想将其视为两个，只需一个。

Answer 1

鉴于您不是按HostName进行分组，看起来您只需要COUNT(DISTINCT x)：

SELECT CipherName, CipherVersion, CipherBits, COUNT(DISTINCT ClientIP) As "Hits" 
from Ciphers
WHERE Hostname like '%domain.com' 
Group by CipherName, CipherVersion, CipherBits;

SqlFiddle here

Answer 2

你可以试试这个 -

SELECT CipherName, CipherVersion, CipherBits, COUNT(DISTINCT ClientIP) OVER (PARTITION BY CipherName, CipherVersion, CipherBits) As "Hits" 
from Ciphers
WHERE Hostname like '%domain.com';