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Using Parameters With Web Queries

Introduction

Excel provides a very useful option to gather data from websites, called web queries. These have been introduced with Excel 97 and have been further enhanced in the versions released after Excel 97. This article shows how you can setup a web query so that you can make the worksheet dynamically update based on values in so called parameter cells.

Setting up the web query

Setting up a web query is as simple as choosing Data, Get External data, New Web Query.

In the next dialog, you enter the URL of the site you want to extract data from. For example:

http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLD,GGLD:2003-44,GGLD:en&q=%22Jan+Karel+Pieterse%22

To make part of the url work as a parameter, replace that part of the url with some text between quotes and square brackets (this will only work when using the URL would open a normal page in a web browser):

http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLD,GGLD:2003-44,GGLD:en&q=["SearchFor"]

Excel will interpret the part between the square brackets as a parameter and prompt you for a value once you click the Import button or when you refresh the query table. The string you entered will be used as both the name of the parameter and the prompt:

The fun thing is, that you can either fill in a value or you can select a cell as an input for the parameter:

By checking the two checkboxes shown above, you ensure that Excel will automatically update the query table when you change the content of the cell(s) you selected.

Working With Web Query Parameters In VBA

Excel VBA offers the programmer access to web query parameters through the Parameters collection of Parameter objects.

Unlike "normal" database queries, it is not possible to add a parameter to the Parameters collection using the Add method (though even for that type of query, doing so is an awkward process).

Instead one has to add all parameters one needs to the Connection string. Excel will determine the number of parameters from that string once it has been applied to the Connection property and then the Parameters collection becomes available to VBA. In the example below, a web query is added to a worksheet. The message box shows, that there are no parameters:

 Sub Demo()
    Dim oSh As Worksheet
    Set oSh = ActiveSheet
    With oSh.QueryTables.Add("URL;http://www.jkp-ads.com", oSh.Range("A1"))
        .BackgroundQuery = False
        MsgBox .Parameters.Count
    End With
End Sub

Result:

If the code shown above is changed to add a parameter in the connection string, things change:

 Sub Demo()
    Dim oSh As Worksheet
    Set oSh = ActiveSheet
    With oSh.QueryTables.Add("URL;http://www.jkp-ads.com/Articles/[""PageName""].htm", oSh.Range("A1"))
        .BackgroundQuery = False
        MsgBox .Parameters.Count
        With .Parameters(1)
            .SetParam xlRange, oSh.Range("H11")
            .RefreshOnChange = True
        End With
    End With
End Sub

Now the messagebox shows:

Note that in the code sample the parameter has been tied to a cell (SetParam method) and that the query is set to update when that cell changes (RefreshOnChange property set to True). The SetParam method is the only way to change the setting of the parameter object from e.g. prompt to Range and to change the range the query parameter uses as its source.

Conclusion

As this article shows, adding a parameter to a web query is relatively easy. The tricky part is the fact that you need to know that parameters can only be added through the connect string (the URL) by using a very specific syntax and that parameters can only be added by changing the connection string.

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