如何将临时变量设置为基于另一个表的值答案

【问题标题】：How do i set a temp variable to a value based from another table如何将临时变量设置为基于另一个表的值
【发布时间】：2014-10-24 20:53:34
【问题描述】：

我正在使用 AdventureWorks 2012 数据库，我完全被这个数据库难住了，

目前为止

alter proc pName
(
@TranID int
)
as
declare @AccountID int
declare @Entered datetime
declare @Type char
declare @Amount money
declare @Service money
declare @WithdrawalDecrease smallint
declare @WithdrawalCount smallint

set @AccountID = (select AccountID 
                  from Transactions
                  where TransID = @TranID)

set @WithdrawalCount = (select WithdrawalCount 
                        from Accounts
                        inner join Transactions on Transactions.AccountID = Accounts.AccountID
                        where Transactions.AccountID = @AccountID)

但是变量取值我做错了什么？

【问题讨论】：

有什么问题？你有错误吗？你收到的价值不是你所期望的吗？我们需要一些工作。
变量不会取值没有错误只是空值
这条语句“select AccountID from TransID = @TranID”返回了多少
我得到 1，值为 7 in，AccountID = 2
你能再清楚一点我没有得到最后的评论

标签： sql join sql-server-2012

【解决方案1】：

语法没有错

SET @AccountID = (SELECT AccountID
                  FROM   Transactions
                  WHERE  TransID = @TranID)
SET @WithdrawalCount = (SELECT WithdrawalCount
                        FROM   Accounts
                               INNER JOIN Transactions
                                       ON Transactions.AccountID = Accounts.AccountID
                        WHERE  Transactions.AccountID = @AccountID)

但在这里，您尝试将 AccountID 设置为 @AccountID，TransID =@TranID。如果您的 Transactions 表有不止一行 @TranID 则最后插入的值将分配给变量所以尝试使用top 1 和order by

SET @AccountID = (SELECT top 1 AccountID
                  FROM   Transactions
                  WHERE  TransID = @TranID order by column)

SET @WithdrawalCount = (SELECT top 1 WithdrawalCount
                        FROM   Accounts
                               INNER JOIN Transactions
                                       ON Transactions.AccountID = Accounts.AccountID
                        WHERE  Transactions.AccountID = @AccountID order by column)

【讨论】：