Question

我想完成类似的事情：

,sell = (select tr.money_value from dpdata.DP_Transaction tr where tr.transaction_type IN (0, 2))
,buy =  (select tr.money_value from dpdata.DP_Transaction tr where tr.transaction_type IN (4))
,SUM(sell - buy)  AS current_balance --Invalid column name

...如上图所示，它在最后一行给出了错误。

Answer 1

错误是，如果您选择一个列并在select语句中给它一个别名，则不能在同一个select语句中将该别名用作列

试试这个： -

,sell = (select tr.money_value from dpdata.DP_Transaction tr where tr.transaction_type IN (0, 2))
,buy =  (select tr.money_value from dpdata.DP_Transaction tr where tr.transaction_type IN (4))
,SUM((select tr.money_value from dpdata.DP_Transaction tr where tr.transaction_type IN (0, 2))
- (select tr.money_value from dpdata.DP_Transaction tr where tr.transaction_type IN (4)))

Answer 2

PowerShell shell = PowerShell.Create().AddCommand("Get-NetAdapter") .AddParameter("name", "Ethernet*") .AddParameter("ThrottleLimit", 5);的回答：

给定的建议很容易发生变化，你也可以通过使用如下的子查询来解决这个问题：

IDictionary parameters = new Dictionary<String, String>();
parameters.Add("name", "Ethernet*");
parameters.Add("ThrottleLimit", 5);

PowerShell shell = PowerShell.Create().AddCommand("Get-NetAdapter")
   .AddParameters(parameters)

这样，当您更改India.Rocket或select sell, buy, sell - buy AS current_balance from ( select sell = sum(select tr.money_value from dpdata.DP_Transaction tr where tr.transaction_type IN (0, 2)) , buy = sum(select tr.money_value from dpdata.DP_Transaction tr where tr.transaction_type IN (4)) ) as Subquery的定义时，您也不会忘记更改sell的定义以防止出现任何差异。

SUM函数中的子查询

2 个答案: