1) it should not be "AnalyzerEngineVersion" as dat_version, it should be "AnalyzerDATVersion"
So it should be
[EPOEvents].[AnalyzerVersion] as [product_version],
[EPOEvents].[AnalyzerEngineVersion] as [engine_version],
[EPOEvents].[AnalyzerDATVersion] as [dat_version],
[EPOProdPropsView_VIRUSCAN].[datver] as [vse_dat_version],
2) which field is exactly the latest virus signature of each client machine??