How to select maximum row value using optimal way
This is the SQL view of a msaccess query for your table
SELECT 
    t1.[lClientId]
    ,MAX(t1.datAccess) AS datAccess
    , MAX((SELECT TOP 1  t2.[lProp1] FROM Table1 AS t2 WHERE t2.[lClientId] = t1.[lClientId] AND t2.[lProp1] IS NOT NULL ORDER BY t2.datAccess  DESC, t2.[lProp1] DESC))  AS lProp1
    , MAX((SELECT TOP 1  t2.[lProp2] FROM Table1 AS t2 WHERE t2.[lClientId] = t1.[lClientId] AND t2.[lProp2] IS NOT NULL ORDER BY t2.datAccess  DESC, t2.[lProp2] DESC))  AS lProp2
    , MAX((SELECT TOP 1  t2.[lProp3] FROM Table1 AS t2 WHERE t2.[lClientId] = t1.[lClientId] AND t2.[lProp3] IS NOT NULL ORDER BY t2.datAccess  DESC, t2.[lProp3] DESC))  AS lProp3
FROM Table1 AS t1
GROUP BY t1.[lClientId];

Result




lClientId
datAccess
lProp1
lProp2
lProp3




5
10.12.2020
3
10
9


6
29.10.2020
9
11
16