SQL 从 2 列中选择数据，如果它不为 NULL，则插入到视图中

Question

我有一个从多个表中提取数据的视图。在视图的一个列中，我需要插入一个帐户代码，该帐户代码可以在其中一个表的贷方或借方列下找到。如果借方栏中有帐户代码，则贷方栏中不会有帐户代码，反之亦然。基本上，如果在任一列中找到帐户代码，我都需要插入它。

由于 UNION，我无法更改视图列。

也许我正在使用错误的关键字搜索此信息，但我似乎找不到我需要的内容。

谢谢。

使用查询更新

    SELECT
DET_YEAR as [Year],
DET_PERIODNUMBR as [Period],
DET_TYPE AS [Type],
'' AS [Status],
DET_Date AS [Tran Date],
'' AS [Supplier],
'' AS [Supplier Name],
DET_DESCRIPTION as [Description],
DET_DIMENSION3 AS [Department],
'' as [Entry Type],
'' as [Detail],
DET_GROSS as [Value],
DET_COSTHEADER as [Project Code],
CH_NAME as [Project Name], 
DET_COSTCENTRE AS [Project Cost Centre],
'' AS [Analysis Code],
'' AS [Analysis Name],
'' AS [Nominal Code],
'' AS [Account Name],
DET_NOMINALDR as [DebitNominal],
DET_NOMINALCR AS [CreditNominal],
NNAME as [Dr/CrNominalName], 
'' AS POH_ORDER_NUMBR,
DET_BATCH_REF


FROM SL_PL_NL_DETAIL WITH (NOLOCK)
LEFT JOIN CST_COSTHEADER WITH (NOLOCK) ON DET_COSTHEADER = CH_CODE
LEFT JOIN CST_COSTCENTRE WITH (NOLOCK) ON DET_COSTCENTRE = CC_CODE AND DET_COSTHEADER = CC_COPYHEADER
INNER JOIN NL_ACCOUNTS WITH (NOLOCK) ON (DET_NOMINALDR = NCODE OR DET_NOMINALCR = NCODE)

WHERE DET_TYPE IN ('JNL', 'VJL') AND DET_BATCH_FLAG = 0 AND DET_YEAR IN ('C', 'N'))

Answer 1

您可以使用 CASE 语句 - 看不到您的表格，我只是猜测，但您可以执行以下操作：

SELECT ....,
    CASE WHEN credit IS NOT NULL THEN credit ELSE debit END AS account_code,
    -- (etc)

当然，如果列不为空，您可以根据需要使用任何其他条件。

Answer 2

如果我理解正确的话，你可以使用ISNULL或COALESCE如下

ISNULL(a.column, b.column)
OR
COALESCE(a.column, b.column....)  
--We can define multiple columns but it will return first NOT NULL value

看看这个例子：

CREATE TABLE #testOne(id int identity(1,1), 
    accountDebit varchar(50), accountCredit varchar(50))

insert into #testOne values
(null, '1222-1020')

select * from #testOne

id  accountDebit    accountCredit
1   NULL            1222-1020

select id, 
    isnull(accountDebit, accountCredit) AS account_code 
from #testOne

输出

id  account_code
1   1222-1020