how to condition a custom dialog in msi installer?

I have a开发者_运维知识库dded a custom dialog in the start stage of my VS2008 created msi installer to allow user choose if he/she wants to update the database or not. But if database is NOT installed yet, that dialog doesn't make sense. So I want to search the database frist, if there is no database installed, that dialog should be ignored. How can do that

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You are trying to make Visual Studio Deployment Projects do things they were not designed to do. It would take extensive knowledge of MSI tables and tons of build automation scripting to manipulate the MSI after it's build. That is to say that if you have to ask the question, you aren't going to be able to do it.

Stop wasting your time with VDPROJ (Microsoft has retired it since even THEY know how much it sucks) and start looking at WiX or InstallShield.