pivot rows to columns and retain one row for one user

Question

id	user	manager_id	manager_name	hierarchy	level_1	level_2	level_3	level_4
100	A	30	peter	1	brian	null	null	null
100	A	null	null	2	null	koby	null	null
100	A	null	null	3	null	null	peter	null
200	B	20	koby	1	null	brian	null	null
200	B	null	null	2	peter	null	null	null
200	B	null	null	3	null	null	koby	null
300	C	10	brian	1	peter	null	null	null
300	C	null	null	2	null	koby	null	null
300	C	null	null	3	null	null	brian	null

How to pivot the rows values to existing columns so as to retain one row for one user?

id	user	manager_id	manager_name	hierarchy	level_1	level_2	level_3	level_4
100	A	30	peter	4	brian	koby	peter	null
200	B	20	koby	4	peter	brian	koby	null
300	C	10	brian	4	peter	koby	brian	null

Note: Each level will have only one value for each user.

Answer 1

Given your premise of one single value on aggregated fields for each user, you can just use aggregation with the MAX funtion for each non-aggregated field:

SELECT id, [user], 
       MAX(manager_id)   AS manager_id, 
       MAX(manager_name) AS manager_name, 
       MAX(hierarchy) +1 AS hierarchy,
       MAX(level_1)      AS level_1, 
       MAX(level_2)      AS level_2, 
       MAX(level_3)      AS level_3, 
       MAX(level_4)      AS level_4 
FROM tab
GROUP BY id, [user]

Check the demo here.