Question

这是我的问题：

This particular table stores information about visits that clients have made so far

“收入”控制者（基本求和）-按天/月/年计

handle_readConnection

从sqlite切换到Postgres使得strftime无法使用-我尝试将其更改为以下内容：

def index
 @days = Visit.select("start_time,SUM(price) as price").group("strftime('%Y-%m-%d', start_time)").where(:start_time => DateTime.now.beginning_of_month..DateTime.now.end_of_month).where(:status => true).order('start_time DESC').all
 @months = Visit.select("start_time,SUM(price) as price").group("strftime('%Y-%m', start_time)").where(:status => true).order('start_time DESC').all
 @years = Visit.select("start_time,SUM(price) as price").group("strftime('%Y', start_time)").where(:status => true).order('start_time DESC').all
 @total = 0
 @years.collect { |x| @total = @total + x.price }
end

但是现在我得到了错误

缺少开始时间

在视图中：

 @days = Visit.select("to_char(start_time, 'YYYY-MM-DD'),SUM(price) as price").group("to_char(start_time,'YYYY-MM-DD')").where(:start_time => DateTime.now.beginning_of_month..DateTime.now.end_of_month).where(:status => true).order("to_char(start_time,'YYYY-MM-DD') DESC").all
 @months = Visit.select("to_char(start_time, 'YYYY-MM'),SUM(price) as price").group("to_char(start_time,'YYYY-MM')").where(:status => true).order("to_char(start_time,'YYYY-MM') DESC").all
 @years = Visit.select("to_char(start_time, 'YYYY'),SUM(price) as price").group("to_char(start_time,'YYYY')").where(:status => true).order("to_char(start_time,'YYYY') DESC").all

我不太明白为什么会出现这样的错误。

Answer 1

要转换date（而不是datetime），可以使用to_date或to_timestamp https://www.postgresql.org/docs/9.6/functions-formatting.html

Answer 2

您还可以使用DateTime＃iso8601将日期转换为字符串

https://ruby-doc.org/stdlib-2.3.3/libdoc/date/rdoc/DateTime.html#method-i-iso8601

Postgres db中strftime的替代方法

2 个答案: