Question

说我有下表，Peter和Halla，

Name    Age occupation  BillingContactEmail
-------------------------------------------
Peter   44  Salesman    a@a.com
Andy    43  Manager     a@a.com
Halla   33  Fisherman   b@b.com

如何构造SQL以返回此数据集：

Name    Age occupation  BillingContactEmail
-------------------------------------------
Peter   44  Salesman    a@a.com
Halla   33  Fisherman   b@b.com

我们只检索电子邮件的实例？（这意味着我们最终会有不同的电子邮件）

Answer 1

试试这个

;with cte (rowno, Name, Age, Occupation, BillingContactEmail)
as (
    select row_number() over (partition by BillingContactEmail order by BillingContactEmail), Name, Age, Occupation, BillingContactEmail 
    from myTable
)
select Name, Age, Occupation, BillingContactEmail from cte 
where  rowno = 1

您可能需要考虑对列进行索引以获得更好的性能。

当然，如果您想具体了解选择对象，则需要相应地调整order by。

如果年龄/职业无关紧要，您可以随时通过电子邮件获取姓名：

select  stuff((select concat( ',', Name) from myTable a where a.BillingContactEmail = t.BillingContactEmail   for xml Path('')), 1, 1, '') as Name, 
        BillingContactEmail 
from myTable t
group by BillingContactEmail

输出：

Name          BillingContactEmail 
------------- --------------------
Peter,Andy    a@a.com
Halla         b@b.com

Answer 2

尝试类似

的内容

Select distinct  email,
        (
           Select tb1.First_Name+ ','  AS [text()]
           From dbo.table1 tb1
           Where tb1.Email = 'a@a.com'
           For XML PATH ('')
        ) [Students]
From dbo.table2
WHERE Email = 'a@a.com'

输出：

Name          BillingContactEmail 
------------- --------------------
Peter,Andy,    a@a.com

检索电子邮件的实例

2 个答案: