c# List獲取重復項

List<Test> t = new List<Test>() { 
                new Test(){id=1,name="車輛"},
                new Test(){id=2,name="車輛"},
                new Test(){id=3,name="飛機"},
                new Test(){id=4,name="火車"},
                new Test(){id=4,name="火車"},
            };
         //同名
            var q = t.GroupBy(x => x.name).Where(x => x.Count() > 1).ToList();
 
            foreach (var item in q)
            {
                Console.WriteLine(item.Key);
            }

sql:

--重復的物品編碼
SELECT COUNT(0) AS num,Code
FROM dbo.Goods 
GROUP BY Code
HAVING COUNT(0)>1
ORDER BY Code