How does a row in subreport link to a a row in main report in the designer? (Crystal Reports)

I have a Crystal Reports report in Vis开发者_运维技巧ual Studio 2008 which has a subreport. The source for each report is a separate datatable. Say main report datatable schema is id1, id2, firstname. subreport has datatable schema: id1, id2, lastname. When the report displays, it displays firstname, lastname for each record.

If the reports are joined by id1, how do I change it so that it's joined by id2 instead in the report designer? I am not very familiar with CR and I can't find where the reports are joined and by which column.

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Tony,

You will need to right click the subreport, and choose Change Subreport Links. This window will pull up a list of available fields and you choose the right arrow to create the link.

Please let me know if this doesn't do the trick.