sql-server - sql server中的分组和计数

Question

我想要一个简单的查询来获得一些输出。记录是

ID      Count
215     1
215     1
215     1
215     1

输出必须是

ID   Count
215  4

Answer 1

SELECT ID, COUNT(*) AS Count
FROM tablename
GROUP BY ID

Answer 2

很简单，

SELECT ID ,COUNT(*) AS CNT
FROM TABLE_NAME
GROUP BY ID

Answer 3

SELECT ID, sum(Count) AS Count
FROM tablename
GROUP BY ID