用slq语句实现除去字段T中重复的项并且按照重复高的将序排序：
ID T
1 1-2
2 2-3
3 3-4
4 1-2
5 2-3

所要结果：
ID T
1 1-2
2 2-3
3 3-4

--示例
DECLARE  @T TABLE  (ID INT,T VARCHAR(10))

INSERT INTO @T SELECT 1 ,'1-2'
UNION ALL SELECT 2,'2-3'
UNION ALL SELECT 3,'3-4'
UNION ALL SELECT 4,'1-2'
UNION ALL SELECT 5,'4-5'
UNION ALL SELECT 6,'4-5'
UNION ALL SELECT 7,'5-6'
UNION ALL SELECT 8,'7-8'
UNION ALL SELECT 9,'7-8'

SELECT MIN(ID) ID ,T FROM @T GROUP BY T HAVING COUNT(*)=1
UNION
SELECT  MIN(ID) ID,T FROM @T GROUP BY T HAVING COUNT(*)>=2

INSERT INTO testtable SELECT 1 ,'1-2'
UNION ALL SELECT 2,'2-3'
UNION ALL SELECT 3,'3-4'
UNION ALL SELECT 4,'1-2'
UNION ALL SELECT 5,'2-3'


select id as ID ,t as  值,count(t) as 重复数  from testtable
group by t
order by count(t) desc