Add support for JSON/YAML/XML of query results

[stuartpa]

Enable:

sqlcmd -Q "select my_col from my_table" --output json

And the output to stdout is json/yaml/xml etc. encoding of the result set. (probably following the server side FOR XML AUTO / FOR JSON AUTO encoding strategy)

[anguspmitchell]

An upvote, or perhaps a question:

I'm looking for CLI tool that can run an MSSQL query/SPROC and print machine-readable output. I'm wondering if it would be easier to write my own or to fork this and add it.

The tool needs to support special characters in varchars (newlines, commas, etc.), multiple result sets, and streaming. I think NDJSON is probably the best format for those constraints, but open to feedback on that front as well.