installation - How to detect SQL Server Express in WiX installer

Question

How do I detect if Sql Server Express is installed and running on a machine in a WiX installer?

I want to check before installing my application and if it's not installed and running, to inform the user that it has to be installed first before installing my application.

Answer 1

Ok, I found by trial and error option that works:

<Property Id="SQLSERVER">
  <RegistrySearch Id="SQLServer" Root="HKLM" Key="SOFTWAREMicrosoftMicrosoft Sql Server" Type="raw" Name="InstalledInstances"/>
</Property>

I define a registry search, and then check its value:

<Condition Message="You don't have SQL Server installed.">
  <![CDATA[SQLSERVER >< SQLEXPRESS]]>
</Condition>