Is it possible to set a default value for a Data Explorer query parameter?
You can link to particular queries and have it fill in the parameters for you . For example, here's your comment score distribution on Stack Overflow.
You can also now save default values directly in your parameters using the
##Param?Default## syntax. To see how this works, look at this live demonstration. Note that this will be the default for everyone running the query, so it makes sense to only use this in cases where the default value will make sense for most people.
Default values can also be used with typed parameters, just make sure to put the default value after the type like
##Param:Type?Default## (and use a default value that's an acceptable value for the type).
You can specify the values in the query string if you're sending the URL to someone. For example: https://data.stackexchange.com/stackoverflow/q/114799/?x=12345
I don't think there's a way to hardcode defaults into the script itself