使用 SQL Server 的列名无效

Question

我想减去从POSquantity到iPay88quantity的值，但出现错误

列名无效

我的代码：

select distinct
    tblCurrTrxIPAY88.strAmount as IPay88,
    tblCurrTrxIPAY88.strPOSOnlineRefNo,
    count(tblCurrTrxIPAY88.strPOSOnlineRefNo) as iPay88quantity,
    b.strCostCentreID,
    b.strPOSOnlineRefNo, 
    count(b.strPOSOnlineRefNo) as POSquantity,
    strPayTypeCode, b.strRemarks as Agency,
    tblMachine.strDesc As KioskName, 
    SUM(b.dblPaidAmt) as POS24,
    SUM(b.dblPaidAmt) - tblCurrTrxIPAY88.strAmount as RMVarince,
    POSquantity - iPay88quantity as Varince
from 
    tblCurrTrxMaster as b
inner join
    tblMachine on b.strMachID = tblMachine.strMachID 
inner join
    tblCurrTrxIPAY88 on b.strPOSOnlineRefNo = tblCurrTrxIPAY88.strPOSOnlineRefNo
where
    strPaymentMethod = '02' 
    and b.dtmCreated >= '1/23/2020' 
    and b.strTransStatus = '01'
group by 
    b.strCostCentreID , b.strPOSOnlineRefNo, b.strPayTypeCode, b.strRemarks, 
    tblMachine.strDesc, tblCurrTrxIPAY88.strAmount, 
    tblCurrTrxIPAY88.strPOSOnlineRefNo

Answer 1

iPay88Quantity 不是表中的列名，它是一个计算字段 - 您需要对基础字段进行数学运算，而不是计算字段，即：

POSquantity - count(tblCurrTrxIPAY88.strPOSOnlineRefNo) as Variance