KwickClips Databases and SQL · 42 sec · free
Does AVG treat NULL as zero?
Short answer. No. It skips it.
Which aggregate counts NULL rows?
COUNT(*).
NULL vs zero
| Kabir | SUM | AVG |
|---|---|---|
| NULL | 316 | 79 |
| 0 | 316 | 63.2 |
Remember
| Aggregates skip NULL |
| Except COUNT(*) |
| NULL is not zero |
Kabir's marks are NULL. Is the average seventy nine or sixty three? NULL is skipped. So avg divides by four. Zero is a real value. Then avg divides by five. Aggregates skip NULL. Count star does not. NULL is not zero.
This clip is from the full lesson: Aggregate Functions: COUNT, SUM, AVG, MAX and MIN — 6 minutes, with the tables, the quick answers and the whole lesson in text.
Useful for: CBSE Class 9 Computer Applications (165), CBSE Class 12 Computer Science (083), CBSE Class 12 Informatics Practices (065)
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