I don't think there is builtin metric for db calls, and even, this may be different per DB technoology ..
What I did :
- I created multidimensional view with expected data
- I added the link to multidimensional view in a text tile.
but I agree, not easy to display requests.
Maybe it would be easier by tagging as keyrequests (if it is always the same requests..) , there are some additional metrics for key requests.
For example : builtin:service.keyRequest.response.client may apply to databases
While I have not done this before, you should be able to do it by creating an MDA, and then creating metrics in the dimensions that you want. You should then be able to pin them to the dashboard.