sql主机，
我不明白这个问题的一部分。在select语句中，有一些看起来像独立的“select语句”，几乎像一个函数。此代码是由blackbaud crm供应商编写的。作为独立的代码，代码中没有连接它们带入数据集中的信息，如您在from子句中看到的那样。最后一个奇怪的项目是，在列别名配偶\u id中，列配偶.reciprocarConstituteId甚至不存在于所引用的表中。有人能解释吗？
谢谢

select
        CONSTITUENT.ID,
        CONSTITUENT.ISORGANIZATION,
        CONSTITUENT.KEYNAME,
        CONSTITUENT.FIRSTNAME,
        CONSTITUENT.MIDDLENAME,
        CONSTITUENT.MAIDENNAME,
        CONSTITUENT.NICKNAME,
        (select SPOUSE.RECIPROCALCONSTITUENTID 
         from dbo.RELATIONSHIP as SPOUSE 
         where SPOUSE.RELATIONSHIPCONSTITUENTID = CONSTITUENT.ID 
           and SPOUSE.ISSPOUSE = 1) as [SPOUSE_ID],
        (select MARITALSTATUSCODE.DESCRIPTION 
         from dbo.MARITALSTATUSCODE 
         where MARITALSTATUSCODE.ID = CONSTITUENT.MARITALSTATUSCODEID) as [MARITALSTATUSCODEID_TRANSLATION]
    From 
        dbo.constituent
    left join 
        dbo.ORGANIZATIONDATA on ORGANIZATIONDATA.ID = CONSTITUENT.ID
    where 
       (CONSTITUENT.ISCONSTITUENT = 1)