If it isn't already selected, click on the Query tab to select it. The Query tab is where we will assign a data source to the panel's queries. With TestData DB set as the default data source, Grafana also sets up Random Walk to be the default query Scenario, so we are now ready to go with both a data source and a query that produces the displayed dataset series.
Before we go into the Query tab, we should probably talk a bit about its purpose. Rather than some similar applications that connect to a single database application, Grafana was designed to be agnostic about data. Grafana data source plugins are not only responsible for presenting a simplified query interface to the Grafana user but also for feeding the returned data into the Grafana 7 unified data model, which is used by many panels. Most Grafana users will find that, even with a simplified query UI, they can make relatively sophisticated queries.
In cases...