Question

我有以下sql查询：

Select Invoices.ID, count(*) invoices
From
   Customers.ID F
   Inner join Invoices p
   On P.ID=F.ID and f.ID = 1
group by p.ID
GO

我想要做的是在p.ID组后面的if语句中使用count（）个发票，但是我似乎无法找到获取该值的方法。我知道我可以通过删除group by子句来进行行计数，但我更愿意得到计数（）发票的值。

Select Invoices.ID, count(*) invoices
From
   Customers.ID F
   Inner join Invoices p
   On P.ID=F.ID and f.ID = 1
group by p.ID
if ("value from count(*) invoices) = 0
  do some stuff here
else
  do some other stuff here
GO

谢谢你的帮助。希蒙

Answer 1

将值放在变量中。像这样：

declare @invoice_id int;
declare @myCount int;

Select @invoice_id = Invoices.ID, @myCount = count(*)
From
   Customers.ID F
   Inner join Invoices p
   On P.ID=F.ID and f.ID = 1
group by p.ID
if (@myCount) = 0
  do some stuff here
else
  do some other stuff here
GO

Answer 2

在查询中使用Case语句

Select Invoices.ID, 
Case When count(*)=0 
 then "do something" 
 else "do something" end AS invoices
From
   Customers.ID F
   Inner join Invoices p
   On P.ID=F.ID and f.ID = 1
group by p.ID
GO

如何在Select语句中获取count返回的值

2 个答案: