declare @tb_aa table([id] int,[Detail] nvarchar(1))
Insert @tb_aa
select 1,N'A' union all
select 1,N'A' union all
select 2,N'A' union all
select 2,N'B' union all
select 3,N'B' union all
select 3,N'B'

SELECT * FROM @TB_AA WHERE DETAIL='A'
UNION ALL
SELECT DISTINCT A.* FROM @TB_AA A
LEFT JOIN (SELECT ID FROM @TB_AA WHERE DETAIL='A' GROUP BY ID) AS T
ON A.ID=T.ID
WHERE T.ID IS NULL 

--结果
id          Detail 
----------- ------ 
1           A
1           A
2           A
3           B

（所影响的行数为 4 行）

declare @tb_aa table([id] int,[Detail] nvarchar(1))
Insert @tb_aa
select 1,N'A' union all
select 1,N'A' union all
select 2,N'A' union all
select 2,N'A' union all
select 2,N'B' union all
select 3,N'B' union all
select 3,N'B'

SELECT * FROM @tb_aa WHERE [Detail] ='A'
UNION ALL
SELECT TOP 1 * FROM @tb_aa WHERE [Detail] ='B' AND ID NOT IN (SELECT ID FROM @tb_aa WHERE [Detail] ='A')
/*
id          Detail
----------- ------
1           A
1           A
2           A
2           A
3           B

*/

DECLARE @a TABLE(id int,  Detail varchar(20))
INSERT @a SELECT 1    ,'A' 
UNION ALL SELECT 1    ,'A' 
UNION ALL SELECT 2    ,'A' 
UNION ALL SELECT 2    ,'A' 
UNION ALL SELECT 2    ,'B' 
UNION ALL SELECT 3    ,'B' 
UNION ALL SELECT 3    ,'B' 

SELECT * FROM @a a WHERE Detail='A'
UNION ALL
(SELECT DISTINCT * FROM @a WHERE id NOT IN (SELECT id FROM @a a WHERE Detail='A'))
--result
/*
id          Detail               
----------- -------------------- 
          1 A
          1 A
          2 A
          2 A
          3 B

（所影响的行数为 5 行）
*/