DataDesk
All topics
NULL handling — practice · DataDesk
DataDesk
How it works
Scenarios
Practice
For trainers
Pricing
Log in
Start free
SQL
NULL handling
IS NULL, COALESCE, NULLIF and NULLs in aggregates.
0
/ 20 solved
All levels
Basic (6)
Intermediate (7)
Advanced (7)
All
To do
Solved
1
Find missing values
Basic
2
Has a value
Basic
3
Replace with COALESCE
Basic
4
Missing manager
Basic
5
NULL in arithmetic
Basic
6
Unknown department
Basic
7
NULLs and aggregates
Intermediate
8
Treat missing as zero in an average
Intermediate
9
NULLIF to avoid divide by zero
Intermediate
10
NOT IN trap
Interview
Intermediate
11
Referred vs organic
Intermediate
12
First available contact
Intermediate
13
NULLs sort where?
Intermediate
14
Comparing possibly-NULL columns
Advanced
15
Fill gaps with the previous value
Interview
Advanced
16
Data completeness report
Advanced
17
NULL-safe join
Advanced
18
Customers missing any contact
Advanced
19
Unpaid fee totals
Advanced
20
Most recent non-null email
Advanced