Sql 窗口函数和分组-如何在分区中从第1行到第3行传播数据？

我的问题如下：

select
    Contact.IndividualID,
    Contact.IndividualID as ContactId,
    Contact.CaseNumber as CaseID,
    [Case].ProgramCode as Benefit,
    Contact.Email as EmailAddress,
    '' as EmailTo,
    Contact.FirstName,
    [Case].CaseProgramIndividualStatusCode,
    [Case].ReviewDueDate as RenewDueDate,
    [Case].ReviewDueDate as BenefitExpirationDate,
    [Case].ProgramCode as ProgramCode,
    pref.Phone as MobileNumber,
    Contact.IsHeadOfHousehold,
    row_number() over (partition by Contact.CaseNumber order by Contact.IsHeadOfHousehold desc) as row
from
    SOMETABLE_Contact_Dev Contact    
inner join
    SOMETABLE_Case_Dev [Case] on Contact.IndividualID = [Case].IndividualID and Contact.CaseNumber = [Case].CaseNumber
left join
    [SSP RE Preferences] pref on Contact.IndividualID = pref.ContactId
where 
    (([Case].RenewalTypeCode = 'AC' and [Case].ReviewStatusCode in ('RI','RR')) or 
    ([Case].RenewalTypeCode = 'PS' and [Case].ReviewStatusCode = 'RI')) and 
        DateDiff(day, getdate(), [Case].ReviewDueDate) = 40 and 
        Contact.Email is not null and
        [Case].ProgramCode in ('KC','KT','CC','MA')

下面是运行此查询的结果集：

这就是我遇到的问题。我想做的是，当存在分区定义的分组时，我想将该组的顶部记录（第1行）的电子邮件地址作为EmailTo字段：

如果没有分组，只需使用EmailTo字段的电子邮件地址即可。最好的方法是什么？

您可以在相关分区上使用

e、 例如，假设您所指的分区与用于行号的分区相同，请在行号行后添加以下行

FIRST_VALUE(Contact.Email) OVER (partition by Contact.CaseNumber order by Contact.IsHeadOfHousehold desc) AS first_email