Search notes:

set-winFileExtAssociation

Associate the extension .ext with the prog id progId. I copied this function from the excellent work of Danysys and the github repository PS-SFTA and then slightly adapted it for my purposes 
set-winFileExtAssociation  png PBrush                   # associate .png with MS Paint
set-winFileExtAssociation .sql applications\code.exe

See also

Powershell module: winFileExtProgId

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