# Sub-Table Template Files

In a database, information about a single subject can be divided between multiple tables. This allows data to be stored more efficiently.

To extract data from multiple tables, you can configure sub-tables by setting the `SubTables` parameter. When you extract data from sub-tables, you need to create a template for the main table and a template for each sub-table.

In the main template file, specify the locations where the data from the sub-tables is included in the document. To do this, insert HTML comments (`<!--comment-->`) where `comment` is the name of a sub-table defined in the configuration file.

For example, if you set `SubTables=Customer` the main template might look like this:

    #DREREFERENCE <!--OrderID-->
    #DREFIELD Date="<!--Date-->"
    #DREFIELD CustomerID="<!--CustomerID-->"
    #DREFIELD Status="<!--Status-->"
    <!--Customer-->
    #DRECONTENT
    Order information
    Date Received: <!--Date-->
    Status: <!--Status-->
    #DREENDDOC

The sub-table template (referenced by `<!--Customer-->`) might look like this:

    #DREFIELD Customer_Title="<!--Title-->"
    #DREFIELD Customer_Name="<!--FirstName--> <!--LastName-->"

Each HTML comment in the sub-table template specifies that data should be inserted from a column in the sub table.

When the connector runs a fetch task, the templates are combined and used to create a single document for each row returned by the query. A resulting document might look like this:

    #DREREFERENCE 012345
    #DREFIELD OrderDate="16/10/2012 15:27:11"
    #DREFIELD Customer="2563"
    #DREFIELD Status="Order complete"
    #DREFIELD Customer_Title="Mr."
    #DREFIELD Customer_Name="John Smith"
    #DRECONTENT
    Order information
    Date Received: 16/10/2012 15:27:11
    Status: Order complete
    #DREENDDOC

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