简单SQL查询-分组依据和计数/求和？

我对SQL很差劲，已经试了几个小时了，有人能告诉我怎么写这个吗

我有一张名为“动物”的表格，上面有“物种和年龄”列。 例如：

+-----------------------+
|  Species   |   Age    |
+-----------------------+
|   Dog      |    3     |  
|------------|----------|
|   Dog      |    18    |
|------------|----------|
|   Cat      |    3     |
|------------|----------|
|   Dog      |    20    |
+-----------------------+

我想弄清楚，对于每个物种，在所有3岁的动物中，该物种占多大比例，而在所有非3岁的动物中，该物种占多大比例

所以一些事情会告诉我，比如：

狗4.5%表示所有3岁动物中有4.5%为狗23%表示所有非3岁动物中有23%为狗

类别7.8%12%

等等

非常感谢

尝试以下查询：

SELECT
    Species,
    100.0 * COUNT(CASE WHEN Age = 3 THEN 1 END) / 
        (SELECT COUNT(*) FROM yourTable WHERE Age = 3) AS 3_pct,
    100.0 * COUNT(CASE WHEN Age <> 3 THEN 1 END) / 
        (SELECT COUNT(*) FROM yourTable WHERE Age <> 3) AS not_3_pct,
FROM yourTable
GROUP BY Species;

分母计算所有3岁动物的数量：

COUNT(CASE WHEN Age = 3 THEN 1 END)

(SELECT COUNT(*) FROM yourTable WHERE Age = 3)

请尝试以下查询：

SELECT
    Species,
    100.0 * COUNT(CASE WHEN Age = 3 THEN 1 END) / 
        (SELECT COUNT(*) FROM yourTable WHERE Age = 3) AS 3_pct,
    100.0 * COUNT(CASE WHEN Age <> 3 THEN 1 END) / 
        (SELECT COUNT(*) FROM yourTable WHERE Age <> 3) AS not_3_pct,
FROM yourTable
GROUP BY Species;

分母计算所有3岁动物的数量：

COUNT(CASE WHEN Age = 3 THEN 1 END)

(SELECT COUNT(*) FROM yourTable WHERE Age = 3)

---

获取3岁以下所有狗类动物的百分比：

declare @p int;
select @p = (100.0 * COUNT(a.Species) / (select COUNT(*) from Animals)) from Animals a
where a.Age = 3 and a.Species = 'dog'
group by a.Species
print CONVERT(NVARCHAR, @p) + '% of animals age 3 are dogs';

---

获取3岁以下所有狗类动物的百分比：

declare @p int;
select @p = (100.0 * COUNT(a.Species) / (select COUNT(*) from Animals)) from Animals a
where a.Age = 3 and a.Species = 'dog'
group by a.Species
print CONVERT(NVARCHAR, @p) + '% of animals age 3 are dogs';

选择姓名、年龄、countage作为事件\计数，countage*100.0/选择count*from animal作为事件\按年龄划分的动物组百分比

---

选择名称、年龄、countage作为事件\u count、countage*100.0/选择count*from animal as event\u percent from animal group by age请添加您尝试的查询。听起来像是家庭作业。你应该告诉我们你正在使用哪个版本的SQL。请添加你尝试的查询。听起来像是家庭作业。你应该告诉我们你正在使用哪个版本的SQL。