Why are you using ticket tags to separate departments instead of using departments? You would have to redefine all standard reports. Also why are you trying to get the last order in a report, I would think thats generally needed for some sort of recall not a report.
If you were able to use departments for this SQL would be the way to go. You can easily get the last order based on department and limit it to a single result. Such as:
SELECT Top 1 Orders.CreatedDateTime, Orders.OrderNumber
FROM Orders INNER JOIN
Departments ON Orders.DepartmentId = Departments.Id
WHERE Departments.Name = 'Cafe'
ORDER BY Orders.Id DESC
Then use {REPORT SQL DETAILS:<handler or sql>;<parameters,1,2>:<fields>:<expressions>:<format>} to define what you’re looking to get in your report.
See: