Assign dashboard query result to variable

Grafana Configuration
1

Hello

In Dashboard settings>Variables>Edit i can create a variable referencing a dashboard i already have.

what is the syntax of querying the dashboard?

ive read this (awaited to find syntax there)

,

and all other places in documentation about dashboards as data sources and queries.

thanks in advance

2

so… my admin updated grafana to latest 8.*
and the dashboard word from that dropdown list for variables completely disappeared.

still i can query grafana as datasource - question is how?