计算SQL中按条件分组的行

Question

我们有一个这样的表：

+----+--------+
| Id | ItemId |
+----+--------+
| 1  | 1100   |
| 1  | 1101   |
| 1  | 1102   |
| 2  | 2001   |
| 2  | 2002   |
| 3  | 1101   |
+----+--------+

我们要计算每个人有多少物品，并向他们显示2件或更多物品。 像这样：

+----+-----------+
| Id | ItemCount |
+----+-----------+
| 1  | 3         |
| 2  | 2         |
+----+-----------+

我们没有计算Id = 3的那个人，因为他只有1个项目。

我们如何在SQL中做到这一点？

Answer 1

SELECT id, COUNT(itemId) AS ItemCount 
FROM YourTable 
GROUP BY id 
HAVING COUNT(itemId) > 1

Answer 2

SELECT id,
       count(1)
FROM   YOUR_TABLE
GROUP  BY id
HAVING count(1) > 1; 

Answer 3

使用此查询

SELECT *
FROM (    
    SELECT COUNT(ItemId ) AS COUNT, Id FROM ITEM 
    GROUP BY Id 
) 

my_select
WHERE COUNT>1

Answer 4

select Id, count(ItemId) as ItemCount
   from table_name 
   group by Id 
   having ItemCount > 1