Question

我有3个查询，实际上计算行数如下：

 select  count(*) from mydb.ISEVAENQUIRY where dated=15/12/2017 group by dated;

select  count(*) from mydb.ISEVAENQUIRY where dated=15/12/2017 and interested='yes' group by dated

select  count(*) from mydb.ISEVAENQUIRY where dated=15/12/2017 and closed='yes' group by dated;

我想解雇three queries at time如何做到这一点？

如何在一个查询中组合它们？请帮帮我。

Answer 1

仅限Mysql，您可以使用以下内容来计算

select  sum(dated='15/12/2017') total,
sum(dated='15/12/2017' and interested='yes') total_interested,
sum(dated='15/12/2017' and closed='yes') total_closed
from mydb.ISEVAENQUIRY 
group by dated;

当sum与表达式一起使用时，它将产生一个布尔值0/1，这样你就可以获得条件计数

Answer 2

在mySQL手册中查看＆＃39; UNION＆＃39;并且＆＃39; UNION ALL＆＃39;，应该做的伎俩;） https://dev.mysql.com/doc/refman/5.7/en/union.html

如何使用mysql在count函数内编写select查询

2 个答案: