在运行Add-Migration命令之前，您应该可以在Package Manager控制台中设置变量，方法是键入

You should be able set the variable in the Package Manager Console before running the Add-Migration command by typing

$env:CENTRAL_APPLICATION_SETTINGS="your value"

然后运行

Add-Migration AppOneBaseMigration -Context AppDbContext -OutputDir Migrations\AppOneMigrations