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Access Cookbook, 2nd Edition [Electronic resources] - نسخه متنی

Ken Getz; Paul Litwin; Andy Baron

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Recipe 18.7 Export Using a Where Clause



18.7.1 Problem


You want to export a subset of rows in
a table that match cartain search criteria instead of exporting the
entire table.


18.7.2 Solution


There are two different approaches you can take, depending on how you want the output
to look. The first approach is to design a query, and export the
query to XML, as shown in the Solution in Recipe 18.5. The second is to use the ExportXML method. (You also could use
an XSLT transform, but that would be inefficient unless you also need
to format the data.)

The

18-07.MDB sample application has a saved
query named qryCarsLessThan40. The SQL Select
statement looks like this:

SELECT Car.CarID, Car.Make, Car.Model, Car.Price
FROM Car
WHERE (((Car.Price)<40000));

When you export the query to an XML file by following the steps in
the Solution in Recipe 18.5, the XML
generated looks like that shown in Figure 18-18.


Figure 18-18. XML generated by a query with a WHERE clause


The

18-07.MDB sample application also has a
function named ExportWhere located in
basExportXML. Instead of using a query, this code
exports the Car table and programmatically applies a WhereCondition
of "Price < 40000":

Application.ExportXML _
ObjectType:=acExportTable, _
DataSource:="Car", _
DataTarget:="c:\test\Where.xml", _
WhereCondition:="Price < 40000"

Figure 18-19 shows the output that is generated.


Figure 18-19. XML generated using ExportXML with a WhereCondition



18.7.3 Discussion


When you create a saved query with a Where clause and export it, each
element is named with the query name,
qryCarsLessThan40, as shown in Figure 18-18. When you use the ExportXML method and supply
the optional WhereCondition argument, then the name of the table,
Car, is used. Although you could rename the query
to something less cumbersome than
qryCarsLessThan40, you cannot name it
Car since there already is a table by that name in
the database.

Using the WhereCondition parameter rather than relying on a query
also provides extra flexibility. You can use code to construct
whatever criteria are needed for the
WhereCondition at runtime, rather than having to
hard-code the criteria into a query.


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