PostgreSQL，返回包含年份发票计数的列

Question

2桌

1. 公司
2. 发票

我想返回以下内容

Company Name  |  invoice_total_2014   | invoice_total_2013
----------------------------------------------------------
Company A     | 2000                  | 1500
Company B     | 1000                  | 1000

所以基本上它正在对invoice_total列进行某种查询，其中函数之间的日期为。

这可以在postgreSQL中使用吗？

Answer 1

select
    name,
    sum(
        total * (extract(year from created_at) = 2014)::integer
    ) as invoice_total_2014,
    sum(
        total * (extract(year from created_at) = 2013)::integer
    ) as invoice_total_2013
from invoice
group by name

将布尔值转换为整数会导致0或1

或传统的case

select
    name,
    sum(
        case extract(year from created_at) when 2014 then total end
    ) as invoice_total_2014,
    sum(
        case extract(year from created_at) when 2013 then total end
    ) as invoice_total_2013
from invoice
group by name