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Self & cross joins — practice · DataDesk
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SQL
Self & cross joins
Join a table to itself and build combinations.
0
/ 20 solved
All levels
Basic (5)
Intermediate (8)
Advanced (7)
All
To do
Solved
1
Employee and manager
Interview
Basic
2
Include the top boss
Basic
3
All combinations
Basic
4
Count the combinations
Basic
5
Same city colleagues
Basic
6
Earns more than the manager
Interview
Intermediate
7
Direct report count
Intermediate
8
Joined before the manager
Intermediate
9
Referral pairs
Intermediate
10
Top referrers
Intermediate
11
Matchday fixtures
Intermediate
12
Calendar of logins
Intermediate
13
Salary differences
Intermediate
14
Skip-level manager
Interview
Advanced
15
Consecutive-day logins
Interview
Advanced
16
Price gaps between products
Advanced
17
Team size per manager tree
Advanced
18
Cumulative total without windows
Advanced
19
Students who beat their classmate
Advanced
20
Missing assignments
Advanced