我有一个包含 2 个字段 GroupId、Member 的表 ALPHA：
GroupId | Member;
A1----------A;
A1----------B;
A1----------C;
A2----------A;
A2----------B;
A3----------A;
A3----------D;
A3----------E;
目标：给定 - A、B、C 的输入 - 我必须查询表以查找是否存在用于这组确切成员的 GroupId。所以，这就是我打算做的：
我计划编写一个存储过程并以某种方式实现目标。但是，我的问题可以通过一个查询来实现……也许是一个自连接。
澄清：(A,B,C) 的集合是 A1 独有的。如果输入 (A,B,C,D)，则查询不应返回 A1。
SELECT GroupID
FROM ALPHA
WHERE Member IN ('A', 'B', 'C')
GROUP BY GroupID
HAVING COUNT(*) = 3
这取决于您在 IN 子句中写出成员列表并在 HAVING 子句中设置成员列表中的（不同）条目数。如果你不能这样生成SQL，那么你必须更加努力。
正如在早期评论中所指出的，这还取决于您希望 A、B、C 三个人（可能还有其他一些人）都是该组成员的组的解释。获得“该组恰好包含三个人，即 A、B、C”的一种方法，不一定是最好的方法，是使用：
SELECT GroupID
FROM ALPHA A1
WHERE Member IN ('A', 'B', 'C')
AND 3 = (SELECT COUNT(*) FROM ALPHA A2 WHERE A2.GroupID = A1.GroupID)
GROUP BY GroupID
HAVING COUNT(*) = 3
这显式检查组中的总人数为 3 并且成员是 A、B 和 C（假设 Alpha(GroupID, Member) 存在唯一约束，因此成员不能被列出两次属于同一组）。
SELECT DISTINCT aa.GroupId
FROM Alpha aa
JOIN Alpha ab ON (aa.GroupId = ab.GroupId)
JOIN Alpha ac ON (aa.GroupId = ac.GroupId)
LEFT OUTER JOIN Alpha ax ON (aa.GroupId = ax.GroupId AND ax.Member NOT IN ('A', 'B', 'C')
WHERE aa.Member = 'A' AND ab.Member = 'B' AND ac.Member = 'C'
AND ax.GroupId IS NULL;
也有涉及的解决方案，GROUP BY但我发现该JOIN解决方案通常具有更好的性能。我通常在 MySQL 中工作，我了解 MS SQL Server 更擅长对查询进行分组。因此，请尝试这两种解决方案，看看哪种方法最适合您使用的 RDBMS 品牌。
到目前为止给出的答案假定 Member 字段对于任何给定的 GroupID 都是唯一的。在我所做的工作中，情况并非如此。而且，如果该组有您正在寻找的内容，加上一些额外的，您需要排除该组。
SELECT
[Alpha].GroupID
FROM
[Alpha]
GROUP BY
[Alpha].GroupID
HAVING
SUM(CASE WHEN [alpha].Member IN ('A','B','C') THEN 1 ELSE 0 END) = 3
AND MIN(CASE WHEN [alpha].Member IN ('A','B','C') THEN 1 ELSE 0 END) = 1
您还可以将 IN 子句替换为连接到包含您正在搜索的成员的表...
SELECT
[Alpha].GroupID
FROM
[Alpha]
LEFT JOIN
[Search]
ON [Search].Member
GROUP BY
[Alpha].GroupID
HAVING
SUM(CASE WHEN [alpha].Member = [search].Member THEN 1 ELSE 0 END) = (SELECT COUNT(*) FROM [search])
AND MIN(CASE WHEN [alpha].Member = [search].Member THEN 1 ELSE 0 END) = 1
试试这个：
declare @YourTable table (GroupID char(2),Member char(1))
insert into @YourTable values ('A1','A')
insert into @YourTable values ('A1','B')
insert into @YourTable values ('A1','C')
insert into @YourTable values ('A2','A')
insert into @YourTable values ('A2','B')
insert into @YourTable values ('A3','A')
insert into @YourTable values ('A3','D')
insert into @YourTable values ('A3','E')
insert into @YourTable values ('A5','A')
insert into @YourTable values ('A5','B')
insert into @YourTable values ('A5','C')
insert into @YourTable values ('A5','D')
SELECT t1.GroupID
FROM @YourTable t1
LEFT OUTER JOIN @YourTable t2 ON t1.GroupID=t2.GroupID AND t2.Member NOT IN ('A', 'B', 'C')
WHERE t1.Member IN ('A', 'B', 'C')
AND t2.GroupID IS NULL
GROUP BY t1.GroupID
HAVING COUNT(*) = 3
输出：
GroupID
-------
A1
(1 row(s) affected)
这是一个完整的解决方案：
在你使用我的功能之前，你需要建立一个“帮助”表，每个数据库只需要这样做一次：
CREATE TABLE Numbers
(Number int NOT NULL,
CONSTRAINT PK_Numbers PRIMARY KEY CLUSTERED (Number ASC)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
DECLARE @x int
SET @x=0
WHILE @x<8000
BEGIN
SET @x=@x+1
INSERT INTO Numbers VALUES (@x)
END
使用这个函数来分割你的字符串，它不会循环并且非常快：
CREATE FUNCTION [dbo].[FN_ListToTable]
(
@SplitOn char(1) --REQUIRED, the character to split the @List string on
,@List varchar(8000) --REQUIRED, the list to split apart
)
RETURNS
@ParsedList table
(
ListValue varchar(500)
)
AS
BEGIN
/**
Takes the given @List string and splits it apart based on the given @SplitOn character.
A table is returned, one row per split item, with a column name "ListValue".
This function workes for fixed or variable lenght items.
Empty and null items will not be included in the results set.
Returns a table, one row per item in the list, with a column name "ListValue"
EXAMPLE:
----------
SELECT * FROM dbo.FN_ListToTable(',','1,12,123,1234,54321,6,A,*,|||,,,,B')
returns:
ListValue
-----------
1
12
123
1234
54321
6
A
*
|||
B
(10 row(s) affected)
**/
----------------
--SINGLE QUERY-- --this will not return empty rows
----------------
INSERT INTO @ParsedList
(ListValue)
SELECT
ListValue
FROM (SELECT
LTRIM(RTRIM(SUBSTRING(List2, number+1, CHARINDEX(@SplitOn, List2, number+1)-number - 1))) AS ListValue
FROM (
SELECT @SplitOn + @List + @SplitOn AS List2
) AS dt
INNER JOIN Numbers n ON n.Number < LEN(dt.List2)
WHERE SUBSTRING(List2, number, 1) = @SplitOn
) dt2
WHERE ListValue IS NOT NULL AND ListValue!=''
RETURN
END --Function FN_ListToTable
您现在可以像这样使用该函数来查询任何列表：
DECLARE @List varchar(100)
SET @List='A,B,C'
declare @YourTable table (GroupID char(2),Member char(1))
insert into @YourTable values ('A1','A')
insert into @YourTable values ('A1','B')
insert into @YourTable values ('A1','C')
insert into @YourTable values ('A2','A')
insert into @YourTable values ('A2','B')
insert into @YourTable values ('A3','A')
insert into @YourTable values ('A3','D')
insert into @YourTable values ('A3','E')
insert into @YourTable values ('A5','A')
insert into @YourTable values ('A5','B')
insert into @YourTable values ('A5','C')
insert into @YourTable values ('A5','D')
SELECT t1.GroupID
FROM @YourTable t1
LEFT OUTER JOIN @YourTable t2 ON t1.GroupID=t2.GroupID AND t2.Member NOT IN (SELECT ListValue FROM dbo.FN_ListToTable(',',@List))
WHERE t1.Member IN (SELECT ListValue FROM dbo.FN_ListToTable(',',@List))
AND t2.GroupID IS NULL
GROUP BY t1.GroupID
HAVING COUNT(*) = (SELECT COUNT(*) FROM dbo.FN_ListToTable(',',@List))
输出：
GroupID
-------
A1
select * from ALPHA where Member in( select Member from ALPHA group by Member with COUNT(*) = 3)
试试这个：
SELECT GroupId
FROM ALPHA
GROUP BY GroupId
HAVING SUM(CASE WHEN Member='A' THEN 1.0
WHEN Member='B' THEN 2.0
WHEN Member='C' THEN 4.0
ELSE 7.31415
END) = 7.0
我的建议是将分隔字符串解析到临时表中，然后尝试这样的事情。
create table #temp(member varchar(10))
create table #groups
(
groupID varchar(2),
member char(1)
)
--#temp holds the members from your delimited string.
--#groups holds your relationships.
select distinct groupID
from #groups
where
(select count(*) from #groups i, #temp t
where i.member = t.member and i.groupID = #groups.groupID) =
(select count(*) from #temp)