If using Power Automate Desktop this is an other syntax.
If using af SQL-execution step like this:
SELECT COUNT(*) Cutomers FROM CUSTTABLE
The you can set a variable step like this:
Set (Customers) To: %QueryResult[0]['Customers']%
You can also use a loop for this:
For Each (CurrentItem) in (QueryResult)
... Set variable (Customers) to: %CurrentItem['Customers']%
... Break Loop
End
Happy coding with Power Automate Desktop https://aka.ms/GetStarted-PAD