ConcatRelated()函数上的字符数限制 [英] Character Limit On ConcatRelated() Function

问题描述

我一直在使用艾伦·布朗(Allen Browne)的ConcatRelated()函数，但是正在意识到使用更大的数据集时，数据是不完整的.

I have been using Allen Browne's ConcatRelated() function but am realizing with larger data sets the data is incomplete.

此函数是否有字符数限制?如果有，是否存在可以实现相同结果的/UDF函数?

Does this function have a character limit, and if it does - is there a different function /UDF that can achieve the same result?

这是函数:-并链接回原始线程 http://allenbrowne.com/func -concat.html

This is the function: - and link back to original thread http://allenbrowne.com/func-concat.html

Public Function ConcatRelated(strField As String, _
    strTable As String, _
    Optional strWhere As String, _
    Optional strOrderBy As String, _
    Optional strSeparator = ", ") As Variant
On Error GoTo Err_Handler
    'Purpose:   Generate a concatenated string of related records.
    'Return:    String variant, or Null if no matches.
    'Arguments: strField = name of field to get results from and concatenate.
    '           strTable = name of a table or query.
    '           strWhere = WHERE clause to choose the right values.
    '           strOrderBy = ORDER BY clause, for sorting the values.
    '           strSeparator = characters to use between the concatenated values.
    'Notes:     1. Use square brackets around field/table names with spaces or odd characters.
    '           2. strField can be a Multi-valued field (A2007 and later), but strOrderBy cannot.
    '           3. Nulls are omitted, zero-length strings (ZLSs) are returned as ZLSs.
    '           4. Returning more than 255 characters to a recordset triggers this Access bug:
    '               http://allenbrowne.com/bug-16.html
    Dim rs As DAO.Recordset         'Related records
    Dim rsMV As DAO.Recordset       'Multi-valued field recordset
    Dim strSql As String            'SQL statement
    Dim strOut As String            'Output string to concatenate to.
    Dim lngLen As Long              'Length of string.
    Dim bIsMultiValue As Boolean    'Flag if strField is a multi-valued field.

    'Initialize to Null
    ConcatRelated = Null

    'Build SQL string, and get the records.
    strSql = "SELECT " & strField & " FROM " & strTable
    If strWhere <> vbNullString Then
        strSql = strSql & " WHERE " & strWhere
    End If
    If strOrderBy <> vbNullString Then
        strSql = strSql & " ORDER BY " & strOrderBy
    End If
    Set rs = DBEngine(0)(0).OpenRecordset(strSql, dbOpenDynaset)
    'Determine if the requested field is multi-valued (Type is above 100.)
    bIsMultiValue = (rs(0).Type > 100)

    'Loop through the matching records
    Do While Not rs.EOF
        If bIsMultiValue Then
            'For multi-valued field, loop through the values
            Set rsMV = rs(0).Value
            Do While Not rsMV.EOF
                If Not IsNull(rsMV(0)) Then
                    strOut = strOut & rsMV(0) & strSeparator
                End If
                rsMV.MoveNext
            Loop
            Set rsMV = Nothing
        ElseIf Not IsNull(rs(0)) Then
            strOut = strOut & rs(0) & strSeparator
        End If
        rs.MoveNext
    Loop
    rs.Close

    'Return the string without the trailing separator.
    lngLen = Len(strOut) - Len(strSeparator)
    If lngLen > 0 Then
        ConcatRelated = Left(strOut, lngLen)
    End If

Exit_Handler:
    'Clean up
    Set rsMV = Nothing
    Set rs = Nothing
    Exit Function

Err_Handler:
    MsgBox "Error " & Err.Number & ": " & Err.Description, vbExclamation, "ConcatRelated()"
    Resume Exit_Handler
End Function

修改
我正在使用VBA并运行Into语句.如果先生成表然后再插入数据，效果会更好吗?

Edit
I am using VBA and running an Into statement. Would it work better if I generated the table first and then insert the data?

当前结构

DoCmd.RunSQL "Select DISTINCT [ImportTable].DSFNum, 

ConcatRelated('[Item]','[ImportTable]','[DSFNum] =' & [DSFNum]) AS Item, 
ConcatRelated('[Count]','[ImportTable]','[DSFNum] =' & [DSFNum]) AS Count 
INTO [OneRowTable] 
FROM [ImportTable]"

推荐答案

所有相关信息都可以在ConcatRelated函数的代码中找到:

All of the relevant information can be found in the code for the ConcatRelated function:

1. 注意:向记录集返回超过255个字符会触发此Access错误: http://allenbrowne.com/bug-16.html

1. Notes: Returning more than 255 characters to a recordset triggers this Access bug: http://allenbrowne.com/bug-16.html

在该页面上可以找到，问题不在于功能，而是Access中的文本字段不能包含那么多字符的事实，可以通过使用诸如此类的内容来解决

As can be found on that page, the problem is not the function, but the fact that a text field in Access can't contain that many characters, and can be fixed by using something like

SELECT ID, MuchText FROM StructureOnly 
UNION ALL
SELECT ID, ConcatRelated(something, table, where) AS MuchText FROM LotsaText;

MuchText是备注字段

使用VBA和记录集的解决方法:

A workaround using VBA and recordsets:

Dim rsSelect As DAO.Recordset
Dim rsInsert As DAO.Recordset
Dim db As DAO.Database
Set db = CurrentDb
Set rsSelect = db.OpenRecordset ("Select DISTINCT [ImportTable].DSFNum FROM [ImportTable]")
Set rsInsert = db.OpenRecordset("OneRowTable")
Do While Not rsSelect.EOF
    rsInsert.AddNew
    rsInsert!DSFNum = rsSelect!DSFNum
    rsInsert!Item = ConcatRelated("[Item]","[ImportTable]","[DSFNum] =" & rsSelect!DSFNum)
    rsInsert!Count = ConcatRelated("[Count]","[ImportTable]","[DSFNum] =" & rsSelect!DSFNum)
    rsInsert.Update
    rsSelect.MoveNext
Loop

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