KwickClips Databases and SQL · 42 sec · free
Why does marks = NULL return no rows?
Short answer. NULL is unknown, so = is never true.
Which test finds rows with a value?
IS NOT NULL.
Remember
| Never = NULL |
| IS NULL: value missing |
| IS NOT NULL: value present |
Kabir has no marks. Why does marks equals NULL not find him? NULL is unknown, so equals is never true. Is NULL finds him. Is not NULL finds the rest. Never write equals NULL. Is NULL finds missing values. Is not NULL finds the rest.
This clip is from the full lesson: SQL Operators: BETWEEN, IN, LIKE and IS NULL — 5 minutes, with the tables, the quick answers and the whole lesson in text.
Useful for: CBSE Class 12 Computer Science (083), CBSE Class 11 Informatics Practices (065), CBSE Class 11 Information Technology (802), ICSE Class 10 Computer Applications
More KwickClips from this lesson
Is 65 included in BETWEEN 65 AND 88?39 sec
What is IN a short form of?36 sec
What does '____' match?41 secVoice-over is AI-generated; the script is written and checked by Kajal Ma'am. Confirm anything you plan around against your official board document. We never ask for a password or an OTP.