SQL：如何在大表中找到重複值

Question

我有一個約200萬個SKU的表。有沒有辦法通過運行select查詢來檢測出現多次sku的情況？

Answer 1

Select SKU 
From table 
Group By SKU 
Having Count(SKU) > 1 

Answer 2

SELECT SKUColumn, COUNT(*) FROM YourTable 
    GROUP BY SKUColumn HAVING COUNT(*) > 1 

Answer 3

select SKU, count(SKU) cnt from table group by SKU having cnt > 1