Question

我执行此查询

SELECT Kd_penyakit, Penyakit,
COUNT(case when Kd_gejala in ('G01','','G03','G04','','','','','','','','','','','','','','','','','','')then 1 else null end) / COUNT(kd_penyakit)*100 AS cases
FROM tbl_casebase 
GROUP BY Kd_penyakit 
ORDER BY cases DESC

，结果就像这样

Kd_penyakit   Penyakit         cases

P01           Tipus Ayam       42.8571
P06           Produksi Telur   25.0000
P03           Salesma Ayam     14.2857
P02           Berak Darah      0.0000
P04           Gumboro          0.0000
P05           Mareks           0.0000

我的问题是如何排除0值，结果就像这样

Kd_penyakit   Penyakit         cases

P01           Tipus Ayam       42.8571
P06           Produksi Telur   25.0000
P03           Salesma Ayam     14.2857

Answer 1

一种方法是使用相同的表达式

在HAVING子句中对其进行过滤

SELECT ...
FROM ...
GROUP BY ...
HAVING COUNT(case when Kd_gejala in ('G01','','G03','G04','','','','','','','','','','','','','','','','','','')then 1 else null end) / COUNT(kd_penyakit)*100 > 0
ORDER BY ...

由于您使用的是mysql，因此可以使用ALIAS编写它，尽管它不是标准做法，只能在mysql中使用，并且ONLY_FULL_GROUP_BY extension被废除。

SELECT ...
FROM ...
GROUP BY ...
HAVING cases > 0
ORDER BY ...

Why does MySQL allow HAVING to use SELECT aliases?

Answer 2

使用exists：

过滤掉聚合前的不需要的行

SELECT Kd_penyakit, Penyakit,
COUNT(case when Kd_gejala in ('G01','G03','G04','') then 1 end) / COUNT(kd_penyakit)*100 AS cases
FROM tbl_casebase 
where exists (
   select 1 from tbl_casebase t2
   where tbl_casebase.Kd_penyakit = t2.Kd_penyakit
   and t2.Kd_gejala in ('G01','G03','G04','')
   )
GROUP BY Kd_penyakit
ORDER BY cases DESC
;

注意，在使用带有count()

的案例表达式时，可以省略“else null”

Sql - 排除0值

2 个答案: