Access中不存在字段时如何插入空白值？

Question

我在 Microsoft Access 中使用 vba 代码一次导入多个 csv 文件，不幸的是，并非所有 csv 文件都具有相同的格式；有些文件只有 [SKU-1]，但有些文件有第二个字段 [SKU-2]。

对于在 csv 文件中同时具有 sku-1 和 sku-2 作为字段的文件，我的代码如下所示，但是，如果文件只有 [SKU-1]，则导入失败并显示“参数太少. 预期 1。

如果字段本身不存在以供从中提取，是否有任何方法可以使用某种 case 语句来删除 SKU-2 的 NULL 值？

CurrentDb.Execute "INSERT INTO MumbyCSV (OrderID, Email, FirstName, LastName, Company, Phone, SecondaryPhone," & _
        "Fax, ApproveStatus, OrderDate, [SKU-1], [SKU-2], Total, ShiptoName, ShipToAddress1, ShipToAddress2," & _
        "ShipToCity, ShipToState, ShipToZip, ShipToCountry, ShippingMethod, Comments)" & _
        "SELECT OrderID, Email, FirstName, LastName, Company, Phone, SecondaryPhone," & _
        "Fax, ApproveStatus, OrderDate, [SKU-1], [SKU-2], Total, ShiptoName, ShipToAddress1, ShipToAddress2," & _
        "ShipToCity, ShipToState, ShipToZip, ShipToCountry, ShippingMethod, Comments " & _
        "FROM [Text;FMT=Delimited;HDR=YES;DATABASE=C:\ImportPath].[test.csv]"

Answer 1

首先检查文件中的字段数：

dim fso : Set fso = CreateObject("Scripting.FileSystemObject")
dim file : Set file = fso.OpenTextFile("C:\ImportPath\test.csv")
firstLine = file.ReadLine ' read first line
fieldArray = Split(firstLine, "whateverfielddelimiteryouhave")
numFields = UBound(fieldArray) + 1  'index on arrays from zero

这将告诉您有多少字段。如果您定义了带有和不带有[SKU-2] 的SQL，那么您可以使用简单的IF 来选择要执行的SQL：

If numFields = 22 Then
sql = "INSERT INTO MumbyCSV (OrderID, Email, FirstName, LastName, Company, Phone, SecondaryPhone," & _
        "Fax, ApproveStatus, OrderDate, [SKU-1], [SKU-2], Total, ShiptoName, ShipToAddress1, ShipToAddress2," & _
        "ShipToCity, ShipToState, ShipToZip, ShipToCountry, ShippingMethod, Comments)" & _
        "SELECT OrderID, Email, FirstName, LastName, Company, Phone, SecondaryPhone," & _
        "Fax, ApproveStatus, OrderDate, [SKU-1], [SKU-2], Total, ShiptoName, ShipToAddress1, ShipToAddress2," & _
        "ShipToCity, ShipToState, ShipToZip, ShipToCountry, ShippingMethod, Comments " & _
        "FROM [Text;FMT=Delimited;HDR=YES;DATABASE=C:\ImportPath].[test.csv]" 
Else
sql = "INSERT INTO MumbyCSV (OrderID, Email, FirstName, LastName, Company, Phone, SecondaryPhone," & _
        "Fax, ApproveStatus, OrderDate, [SKU-1], Total, ShiptoName, ShipToAddress1, ShipToAddress2," & _
        "ShipToCity, ShipToState, ShipToZip, ShipToCountry, ShippingMethod, Comments)" & _
        "SELECT OrderID, Email, FirstName, LastName, Company, Phone, SecondaryPhone," & _
        "Fax, ApproveStatus, OrderDate, [SKU-1], Total, ShiptoName, ShipToAddress1, ShipToAddress2," & _
        "ShipToCity, ShipToState, ShipToZip, ShipToCountry, ShippingMethod, Comments " & _
        "FROM [Text;FMT=Delimited;HDR=YES;DATABASE=C:\ImportPath].[test.csv]"
End If

CurrentDB.Execute sql

第二个选项是读取要导入数组的值，如果该值是空字符串，则将其替换为 NULL，这样该字段就不会在 INSERT 步骤中设置。但是，如果您必须根据您的代码直接从文件中导入，我认为您不能这样做。

Answer 2

考虑使用TransferText，它不需要任何列顺序并忽略丢失的列，只要当前正在导入的文件在表中的某处维护列：

DoCmd.TransferText acImportDelim, , "MumbyCSV", "C:\ImportPath\test.csv", True