如何在SQL选择查询中添加大小写表达式

Question

我尝试了以下查询来获取客户的收款明细。在此案例陈述中出了什么问题？我需要的是显示付款类型（如果有金额）。

select convert(varchar,a.DocDate,110) as DocDate,
       a.CardCode,
       a.CardName,
       d.SlpName,
       e.CheckNum,
       (case when a.CashSum >= 0 then "Cash Payment" when a.CreditSum >= 0 then "Credit Card Payment" when a.CheckSum >= 0 then "Cheque Payment" else "Bank Transfer" end) as 'Payment type',
       (ISNULL(a.CashSum,0) + ISNULL(a.CreditSum,0) + ISNULL(a.CheckSum,0) + ISNULL(a.TrsfrSum,0)) as DocTotal 
from ORCT a
left join RCT2 b on b.DocNum=a.DocNum
Left Join OINV c on c.DocNum = b.DocEntry
Left join OSLP d on d.SlpCode = c.SlpCode
left join RCT1 e on e.DocNum = a.DocEntry

它给出以下错误

Answer 1

在SQL Server中，文字字符串括在单引号'中，而不括在双引号"中。

另一方面，列（对象）名称包含在括号[Payment type]或双引号"Payment type"中。

因此，您的查询应类似于：

case 
    when a.CashSum >= 0 then 'Cash Payment' 
    when a.CreditSum >= 0 then 'Credit Card Payment'
    when a.CheckSum >= 0 then 'Cheque Payment'
    else 'Bank Transfer' 
end as [Payment type]

Answer 2

在THEN块中的以下case表达式中，将双引号替换为单引号：

(case when a.CashSum >= 0 then "Cash Payment" when a.CreditSum >= 0 then "Credit Card Payment" when a.CheckSum >= 0 then "Cheque Payment" else "Bank Transfer" end) as 'Payment type',

到

(case when a.CashSum >= 0 then 'Cash Payment' when a.CreditSum >= 0 then 'Credit Card Payment' when a.CheckSum >= 0 then 'Cheque Payment' else 'Bank Transfer' end) as 'Payment type',

db <>小提琴演示的示例：

在THEN中使用dobule quotes时收到错误

在THEN中更改为single quotes后的工作