SQL 按结果计数排序

Question

我有一个表格，其中包含如下数据：

Meal ID   |   Child    |  Fruit

1              Child A     Apple
2              Child B     Orange
3              Child A     Banana
4              Child A     Orange
5              Child C     Banana
6              Child A     Banana
7              Child C     Banana
8              Child A     Banana

我需要根据吃的水果来排序结果，从高到低，例如如果搜索查询是香蕉，结果将显示如下：

Banana Eaters (Highest to Lowest)

Child   |   Number of Bananas eaten

Child A     3
Child C     1

我会开始：

 $sql = "SELECT * FROM meals WHERE Fruit = 'Banana'";

但是我如何将唯一的个人香蕉食者排序为他们自己的条目，然后按吃得最多的人排序结果？

Answer 1

按子分组并使用条件聚合：

select child, sum(fruit = 'Banana') `Number of Bananas eaten`
from meals
group by child
order by `Number of Bananas eaten` desc 

如果您想排除没有香蕉的孩子：

select child, sum(fruit = 'Banana') `Number of Bananas eaten`
from meals
group by child
having `Number of Bananas eaten` > 0
order by `Number of Bananas eaten` desc 

请参阅demo。

Answer 2

用例当

select child,sum(case when Fruit='Banana' then 1 else 0 end) as bananaeaten
from meals
group by child
order by bananaeaten desc

Answer 3

select Child, count(*) as 'Number of bananas eaten' from meals
where Fruit = 'Banana'
group by Child
order by count(*) desc

Answer 4

如果你不想看到“孩子B”，那么在聚合之前过滤：

select Child, count(*) as num_bananas
from meals
where Fruit = 'Banana'
group by Child
order by count(*) desc;