问题描述
我正在尝试使用 DAO.QueryDef
和 Microsoft Access 中的本地 Append
查询来更新 SQL 服务器数据库.我的一些正在更新的字段包含非常长的字符串(从 0
到 700
个字符以上的任意位置).
I'm trying to update a SQL server database using DAO.QueryDef
and a local Append
query in Microsoft Access. Some of my fields that are being updated contain very long strings (anywhere from 0
to upwards of 700
characters).
当字符串长度在 0
到 255
个字符的范围内时,我可以将它传递到我的查询中并更新相应的表.但是,当它们超过 255
个字符时,我收到以下运行时错误:
When the string length is in the range from 0
to 255
characters, I have no problem passing it into my query and updating the respective tables. However when they exceed 255
characters, I receive the following run-time error:
我一直在使用一个随机字符串生成器网站 创建和测试不同长度的字符串.我还检查了我的数据库中的列数据类型,它们都是 NVARCHAR(MAX)
需要的地方.Microsoft Access 显示数据类型为 Long text
的相同列.
I have been using a random string generator website to create and test strings with varying lengths. I have also checked my database for the column data types and they are all NVARCHAR(MAX)
where they need to be. Microsoft Access is showing the same respective columns with the data type Long text
.
请参阅下面的代码片段:
See below for my code snippet:
Dim dbs As DAO.Database
Dim qdf As DAO.QueryDef
Set dbs = CurrentDb
If Not IsNull(cmbboxFileNameLogic) Then
Set qdf = dbs.QueryDefs("qryUpdateFile")
qdf.Parameters("FileName").Value = txtboxUpdateConversionName.Value
qdf.Parameters("ZipFileName").Value = txtboxZipFileNameLogic.Value
qdf.Parameters("OutputFormat").Value = txtboxOutputFormat.Value
qdf.Parameters("Delimeter").Value = txtboxDelimeter.Value
qdf.Parameters("DestinationLocation").Value = txtboxDestinationLocation.Value
qdf.Parameters("DeliveryMechinism").Value = txtboxDeliveryMechinism.Value
qdf.Parameters("Note").Value = txtboxOutputFileInfoNotes.Value
qdf.Parameters("Criteria").Value = txtboxOutputFileInfoCriteria.Value
qdf.Parameters("CustomListKey").Value = txtboxCustomListKey.Value
qdf.Parameters("ExcludeCustomListKey").Value = txtboxExcludeCustomListKey.Value
qdf.Parameters("NewspaperFlag").Value = chkNewsPaperFlag.Value
qdf.Parameters("WebsiteFlag").Value = chkWebsiteFlag.Value
qdf.Parameters("MarketingFlag").Value = chkProfessionalMarketingFlag.Value
qdf.Parameters("PrintFlag").Value = chkProfessionalPrintFlag.Value
qdf.Parameters("WebsiteFlag").Value = chkWebsiteFlag.Value
qdf.Parameters("BrokerDealerFlag").Value = chkBrokerDealerFlag.Value
qdf.Parameters("ActiveOnly").Value = chkActiveOnly.Value
qdf.Parameters("OutputFormatting").Value = txtboxFileFormatting.Value
qdf.Parameters("Header").Value = txtboxHeader.Value
qdf.Parameters("Footer").Value = txtboxFooter.Value
qdf.Parameters("SQLStatement").Value = txtboxSQLStatement.Value
qdf.Parameters("OrderBy").Value = txtboxOrderBy.Value
qdf.Parameters("FileID").Value = cmbboxFileNameLogic.Value
qdf.Execute dbSeeChanges
qdf.Close
lblOutputFileInfoAction.Caption = "File successfully updated"
lblOutputFileInfoAction.Visible = True
Else
-- Insert new values
End If
查询定义:
UPDATE myTableNameGoesHere SET fldFileNameLogic = [FileName],
fldZipFileNameLogic = [ZipFileName],fldOutputFormat = [OutputFormat],
fldDelimeter = [Delimeter],
fldDestinationLocation = [DestinationLocation], fldDeliveryMechinism = [DeliveryMechinism],
fldNote = [Note], fldCriteria = [Criteria], fldCustomListKey = [CustomListKey],
fldExcludeCustomListKey = [ExcludeCustomListKey], fldNewspaperFlag = [NewspaperFlag],
fldProfessionalWebsiteFlag = [WebsiteFlag], fldProfessionalMarketingFlag = [MarketingFlag],
fldProfessionalPrintFlag = [PrintFlag], fldWebsiteFlag = [WebsiteFlag],
fldBrokerDealerFlag = [BrokerDealerFlag], fldActiveOnly = [ActiveOnly],
fldFileOutputFormatting = [OutputFormatting], fldHeader = [Header],
fldFooter = [Footer], fldSQLStatement = [SQLStatement], fldOrderBy = [OrderBy]
WHERE [fldFileID] = [FileID];
推荐答案
您正面临 Access SQL 文本参数的限制.它们不能容纳超过 255 个字符的字符串值.
You're facing a limitation of Access SQL text parameters. They can not accommodate string values longer than 255 characters.
这是一个演示问题的简单示例.
Here is a simple example which demonstrates the problem.
Dim db As DAO.Database
Dim qdf As DAO.QueryDef
Dim strUpdate As String
Dim strLongString As String
strLongString = String(300, "x")
strUpdate = "UPDATE tblFoo SET memo_field = [pLongString] WHERE id=2;"
Set db = CurrentDb
Set qdf = db.CreateQueryDef(vbNullString, strUpdate)
qdf.Parameters("pLongString").Value = strLongString
qdf.Execute dbFailOnError
该代码触发错误 #3271,无效的属性值." ...与您看到的错误相同.
That code triggers error #3271, "Invalid property value." ... the same error you're seeing.
如果我将 UPDATE
语句更改为包含这样的 PARAMETERS
子句...
If I change the UPDATE
statement to include a PARAMETERS
clause like this ...
strUpdate = "PARAMETERS [pLongString] LongText;" & vbCrLf & _
"UPDATE tblFoo SET memo_field = [pLongString] WHERE id=2;"
...结果还是错误#3271.
... the outcome is still error #3271.
我认为没有任何方法可以克服 Access SQL 限制.
I don't believe there is any way to overcome that Access SQL limitation.
因此,如果您的文本参数值的长度大于 255 个字符,则需要不同的方法.
So if the length of your text parameter value is greater than 255 characters, you need a different method.
DAO.Recordset
方法是在字段中存储长文本字符串的简单替代方法.
A DAO.Recordset
approach is a simple alternative to store long text strings in a field.
Dim rs As DAO.Recordset
Dim strSelect
strSelect = "SELECT id, memo_field FROM tblFoo WHERE id=2;"
Set rs = db.OpenRecordset(strSelect)
With rs
If Not (.BOF And .EOF) Then
.Edit
!memo_field.Value = strLongString
.Update
End If
.Close
End With
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