Selecting all from one table and a MAX value from another table

[Greg Knox]

I have two tables: Sessions and SessionData

Sessions
--------------
SessionID
DateCreated

SessionData
--------------
SessionDataID
SessionID
DataTime

I'm wanting to grab all rows from Sessions and then to figure out the length of each session I'm wanting to grab the MAX DataTime value from SessionData.

I'm trying this query but it's not getting the result I want...

SELECT s.*, MAX(d.X) FROM Sessions AS s LEFT JOIN SessionData AS d ON s.SessionID = d.SessionID ORDER BY s.DateCreated DESC

I'd like to end up with a list of Session IDs, DateCreated, and then the maximum DataTime that relates to each Session. Something like...

1, 2019-07-03, 4839
2, 2019-07-02, 4011
3, 2019-07-01, 3281

What am I missing?

Thanks!