将查询结果分配给变量以用于 case 语句

Question

我正在尝试获取总样本列的平均值，并与每个特定记录的列值进行比较。

我在 SQL 服务器中通过声明一个变量然后将其设置为查询结果来完成此操作。

我想在 PG 中做同样的事情，但我没有成功。

在下面的示例中，myconstant2 由于硬编码值而有效，但 myconstant 无效，因为该值设置为单行查询结果。

这里有任何指示吗？

with myconstant (var1) as 
(
    values (select AVG(ptb_account_score_c) 
            from salesforce_production.accounts)
),
myconstant2 (var2) as 
(
     values(6)
)
select
    Id,
    ptb_account_score_c,
    var1,
    var2,
    case 
       when ptb_account_score_c > var1 then 1 else 0 
    end as Blah
from
    salesforce_production.accounts, myconstant, myconstant2

Answer 1

你不需要values:

WITH
       myconstant1 as (select AVG(ptb_account_score_c) as val from salesforce_production.accounts),
       myconstant2 as (select 6 as val)
SELECT Id, ptb_account_score_c, myconstant1.val,
       myconstant2.val,
       case when ptb_account_score_c > myconstant1.val then 1 else 0 end as Blah
  FROM salesforce_production.accounts,myconstant1,myconstant2

Answer 2

我想你只是想要一个 window 函数：

select a.*,
       (case when ptb_account_score_c > avg(a.ptb_account_score_c) over () then 1 else 0 end) as Blah
from salesforce_production.accounts a;

如果需要，您可以将这些组合成一个 CTE：

with params as (
    select AVG(ptb_account_score_c) as var1, 6 as var2
    from salesforce_production.accounts
   )
select a.id, a.ptb_account_score_c,
       params.var1, params.var2,
       (case when a.ptb_account_score_c > params.var1 then 1 else 0 end) as Blah
from salesforce_production.accounts a cross join
     params;

将查询结果分配给变量以用于 case 语句

Assign Results from query to variable for use in case statement

sql

postgresql

analytics

case