You cannot get all fields within a single AdWords API report - some combinations of fields are not allowed.
For instance, see the
docs of ConversionTypeName, and clicks on "Not compatible with the following fields".
To get information into SQL Server, you may like to look in SSIS packages working with AdWords API. Do remember that the AdWords API version changes regularly, so check how often the package is updated.
However, if you
- Hate working with SSIS, or
- Need informative error messages when something goes wrong, or
- Need special processing for certain fields, like importing field "date" into a datetime column (the API sends a string), or strip percentage signs from certain fields (so you can import that into a numeric field), etc.etc.
then you are probably better off writing a dedicated C# program.
You could also look into AwReporting, an open source initiative by Google, but I don't think it connects with SQL Server, and I'm not sure whether fields can have preprocessing.
But, in your case I recommend that you first determine which fields you really need. "All fields" is probably way too much, and if you don't need fields requiring special processing it could be easy.