子查询在 sqlc# 中返回超过 1 个值

Posted 2023-03-24

【中文标题】子查询在 sqlc# 中返回超过 1 个值

【英文标题】：Subquery returned more than 1 value in sqlc#

【发布时间】：2016-01-06 12:31:34

【问题描述】：

在 ADO.Net 中运行的 SQL 命令字符串。问题它可能在子查询中返回超过 1 行。

string str = "
select 
 (select (quantity) from Orderinfo where iron=1 and rno=o.rno) as iron
 ,(select (quantity) from Orderinfo where wash=1 and rno=o.rno) as wash 
 ,(select (quantity) from Orderinfo where dryclean=1 and rno=o.rno) as dryclean 
 ,o.rno
 ,o.id
 ,o.name
 ,(select sum(convert(int,d.quantity)) from orderinfo as d where d.rno=o.rno) as quantity
 ,o.status 
from orderinfo as o 
where o.status='Order in Process' 
group by o.rno,o.id ,o.status ,o.name";

【问题讨论】：

使用 select top 1....... 代替。

请谨慎对待您的 SQL 查询，它们应该与您的应用程序代码一样具有可读性、可维护性和清晰性。

【参考方案1】：

如果我正确理解你想要的结果，你需要得到数量的总和：

string str = "
select 
 (select sum(quantity) from Orderinfo where iron=1 and rno=o.rno) as iron
 ,(select sum(quantity) from Orderinfo where wash=1 and rno=o.rno) as wash 
 ,(select sum(quantity) from Orderinfo where dryclean=1 and rno=o.rno) as dryclean 
 ,o.rno
 ,o.id
 ,o.name
 ,(select sum(convert(int,d.quantity)) from orderinfo as d where d.rno=o.rno) as quantity
 ,o.status 
from orderinfo as o 
where o.status='Order in Process' 
group by o.rno,o.id ,o.status ,o.name";

顺便说一句，我假设您希望整个“o.rno”的数量独立于特定的“o.id”是正确的。否则不需要子查询。