Difference between revisions of "Microsoft Access VBA Code Snippets"

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== ActiveX Data Objects (ADO) ==
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== General ==
 +
 
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=== ActiveX Data Objects (ADO) ===
 
Retrieving and processing a recordset works like this
 
Retrieving and processing a recordset works like this
  
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</syntaxhighlight>
 
</syntaxhighlight>
  
== Setter and Getter ==
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=== Setter and Getter ===
 
In order to store and retrieve settings from the user's registry, it is wise to implement Setters and Getters. The general code for a variable named "Id" of the variable type "Long" looks like this:
 
In order to store and retrieve settings from the user's registry, it is wise to implement Setters and Getters. The general code for a variable named "Id" of the variable type "Long" looks like this:
  

Revision as of 14:05, 1 July 2010

General

ActiveX Data Objects (ADO)

Retrieving and processing a recordset works like this

    Dim cn As ADODB.Connection
    Dim rs As ADODB.Recordset
    
    Set cn = CurrentProject.Connection
    Set rs = New ADODB.Recordset
    With rs
        .Open _
            Source:="SELECT * FROM tblTable", _
            ActiveConnection:=cn
        .MoveFirst
        Do While Not .EOF
            'Record based instructions
            .MoveNext
        Loop
        .Close
    End With

Setter and Getter

In order to store and retrieve settings from the user's registry, it is wise to implement Setters and Getters. The general code for a variable named "Id" of the variable type "Long" looks like this:

10 Public Sub setId(lngId As Long)
11     SaveSetting getProjectName, "RunTime", "Id", CStr(lngId)
12 End Sub
20 Public Function getId() As Long
21     Dim lngResult As Long
22     
23     lngResult = CLng(GetSetting(getProjectName, "RunTime", "Id", 0))
24     
25     getId = lngResult
26 End Function

A few remarks on this code:

  • Lines 11 and 23: "RunTime" just indicates that the variable will change frequently while working with the database. You may want to use different "categories" for your settings such as "RunTime", "Import", "User" and so on in order to reflect either the scope or the frequency of the settings. If you are using distinct namespaces like this, you should consider putting the namespace into the names of the functions, so that on the one hand it is possible to tell from the names which settings are meant and on the other hand you could reuse a term like Id in both namespaces; example: getId vs getImportId
  • Lines 11 and 23: The setting's name ("Id") should be the same that the functions have ("setId", "getId").
  • Lines 10, 20ff: The variable type should always be converted explicitly, although VBA is able to cast implicit conversions (like strResult = datNow).

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