Question

这绝对没问题

Update TradeFlow 
set flt_TotalPriceUSD= 
(Select top 1 (flt_ExRate * TradeFlow.flt_TotalPrice) 
from ExchangeRate ex inner join DateConversion dc 
on ex.dtm_Date = dc.gDate and  pDate=Convert(varchar,'01') + '/' 
+  Convert(varchar,'03') + '/' + Convert(varchar,'1389'))

但是当我用数据库中的值（TradeFlow.int_Month和TradeFlow.int_Year）替换它时，它就会停止工作。 pdate是一个字符串

Update TradeFlow 
set flt_TotalPriceUSD = (Select top 1 (flt_ExRate * TradeFlow.flt_TotalPrice)
from ExchangeRate ex inner join DateConversion dc   
on ex.dtm_Date = dc.gDate and  pDate=Convert(varchar,'01') + '/' +  
Convert(varchar,TradeFlow.int_Month) + '/' 
+ Convert(varchar,TradeFlow.int_Year))

任何想法为什么？

Answer 1

我的建议：

而不是：

Convert(varchar,TradeFlow.int_Month) ...
Convert(varchar,TradeFlow.int_Year))

写：

right( '0' + rtrim(ltrim(str(TradeFlow.int_Month))), 2) ...
right( '0000' + rtrim(ltrim(str(TradeFlow.int_Year))), 4) ...

Answer 2

Update TradeFlow 
set flt_TotalPriceUSD= (Select top 1 (flt_ExRate * TradeFlow.flt_TotalPrice) 
    from ExchangeRate ex inner join DateConversion dc   
on ex.dtm_Date = dc.gDate and  
    --if pDate is varchar type (`dd/MM/yyyy`)
    pDate= '01/' + right('0' + cast(TradeFlow.int_Month as varchar), 2) + '/' + 
        cast(TradeFlow.int_Year as varchar)

    --if pDate is datetime type
    pDate=  cast(TradeFlow.int_Year as varchar) + 
        right('0' + cast(TradeFlow.int_Month as varchar), 2) + '01'

SQL查询转换

2 个答案: