查询：如果列为空，则添加条件

Question

我正在使用存储过程处理此查询。简化术语的数据结构如下所示：包含表格的表格：

• 人
• Elec_Nominations
• Elec_Vacancy
• 沃德
• 扇区

为病房内的某个部门设置了多个空置座位。被提名为席位的个人将被输入Person数据库并链接到Elec_Nominations。此提名与Ward到Elec_Vacancy相关联。提名也与部门（ELEC_SPEAKER_SECTOR）到Elec_Vacancy以及一些其他链接表相关联：

我正在处理的查询

SELECT DISTINCT
    p.PERSON_ID,
    p.ID_NUMBER,
    CONCAT(p.FULLNAMES, (CONCAT((' ' COLLATE Latin1_General_CI_AS), p.SURNAME))) AS NAME,
    o.ORG_NAME,
    eiw.INTEREST_WARD_ID,
    scw.SUBCOUNCIL_ID,
    w.WARD_ID,
    ess.SPEAKER_SECTOR_ID,
    (SELECT TOP 1
     essg.NO_OF_SEATS
     FROM
         ELEC_SPEAKER_SECTOR_GROUP essg
         INNER JOIN ELEC_VACANCY ev ON essg.VACANCY_ID = ev.VACANCY_ID
     WHERE
         ev.VACANCY_ID = en.VACANCY_ID
     ORDER BY
         essg.ELEC_SECTOR_GROUP_SECTORS_ID DESC) AS SECTORSEATS,
    en.SECTOR_TEXT AS SECTORTEXT
    --essg.NO_OF_SEATS AS [SECTORSEATS]
FROM
    PERSON p
RIGHT OUTER JOIN 
    ELEC_NOMINATIONS en ON p.PERSON_ID = en.PERSON_ID
RIGHT OUTER JOIN 
    ELEC_INTEREST_WARD eiw ON en.INTEREST_WARD_ID = eiw.INTEREST_WARD_ID
LEFT JOIN 
    ELEC_INTEREST_GROUP eig ON eiw.INTEREST_GROUP_ID = eig.INTEREST_GROUP_ID
LEFT JOIN 
    ORGANISATION o ON eig.ORG_ID = o.ORG_ID
LEFT JOIN 
    WARD w ON eiw.WARD_ID = w.WARD_ID
LEFT JOIN 
    ELEC_SPEAKER_SECTOR ess ON eiw.SPEAKER_SECTOR_ID = ess.SPEAKER_SECTOR_ID
LEFT JOIN 
    SUBCOUNCILWARD scw ON w.WARD_ID = scw.WARD_ID
    --INNER JOIN ELEC_VACANCY ev ON en.VACANCY_ID = ev.VACANCY_ID
    --INNER JOIN ELEC_SPEAKER_SECTOR_GROUP essg ON ev.VACANCY_ID = essg.VACANCY_ID
WHERE
    ess.SPEAKER_SECTOR_ID IN (SELECT s.item FROM ufn_SplitIntArray(@P_Sectors, ',') s)
    AND w.WARD_ID IN (SELECT s.item FROM ufn_SplitIntArray(@P_Wards, ',') s)
    AND o.ORG_ID = @P_Org_ID
    --AND en.ELECTED = 1
ORDER BY
    w.WARD_ID

此查询的输出将进入此GridView：

好的，我仍然需要从客户那里了解如何确定行业席位。问题在于，如果我说en.Elected = 1，它只显示被选举的人，但它没有显示甚至没有空缺的部门和病房（即第3和第5）行不会显示。）

当我打字时，我想到了什么。我会尝试研究以确定我是否可以这样做：

AND EVAL(ISNULL(en.NOMINATION_ID, 1))

或SQL中的某些内容：

if(en.NOMINATION_ID == null)
    true
else
    en.Elected == true

Answer 1

用例子句：

and columnfilter = case when columnempty is null then (condition) else columnfilter

另外，请参阅这些回答：
SQL Server 2012 - Case statement in where clause
"CASE" statement within "WHERE" clause in SQL Server 2008