请使用下面的查询，

select COUNT(distinct testID)  from PRODUCT where CLASS_TYPE = 'test'

你想要什么 count(distinct) :

select count(distinct testID)
from product p
where p.class_type = 'test'

如果要获取总计数和副本，可以尝试以下sql：

SELECT count(DISTINCT testID) as distinct_elements, count(*) as total_elements, 
      (count(*) - count(DISTINCT testID)) as duplicate_elements 
FROM PRODUCT
WHERE CLASS_TYPE = 'test';

你可以用 distinct :

select count(distinct col) as Unique_CNT, COUNT(*) as all_CNT  
from PRODUCT 
where CLASS_TYPE = 'test';

CREATE TABLE #Test
( 
testID VARCHAR(100)   
) 

INSERT INTO #Test
(testID)
VALUES
('1234-00-01'),
('1234-00-01'),
('1234-00-02'),
('1234-00-02'),
('1111222233')

select COUNT(distinct testID) from #Test