mysql - Why in SQL NULL can't match with NULL?

Question

I'm new to SQL concepts, while studying NULL expression I wonder why NULL can't match with NULL can anyone tell me a real world example to simply this concept?

Answer 1

Rule : Not even a NULL can be equal to NULL.

A Non-Technical aspect

If you ask two girls, how old they are? may be you would hear them to refuse to answer your question, Both girls are giving you NULL as age and this doesn't mean both have similar age. So there is nothing can be equal to null.