[Dxbase] Selection Wizard question

[David VE3VID]

I have found discrepancies between some of my online logs and my main DXbase log.  QSOs that are present on the online log are missing from my main DXbase log.
If I use the Selection Wizard to export an ADIF file,  are those QSOs removed from my main .mdb file?  Or does the selection wizard simply copy those QSOs to the new ADIF file?I'm confused about how these contacts became lost from my log file 
Thanks for any help,David

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