Visualize Percentage with MSSQL Query and Pie Chart


I am trying to visualize a donut with the Pie Chart plugin using a ms-sql query.

I set ‘Format As’ to ‘Table’.

My query looks like this:

Select TOP 1 (currentNumber)/(totalNumber) from someTable

It returns a percentage value like 0.89988.
How can I achieve Grafana Pie Chart to visualize the percentage of this value in a donut?

At the moment it still says ‘Cannot read property length of undefined’.

What am I doing wrong? Do I need to specify an alias named ‘length’?