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What Happens If NULL Values Are Involved in Expressions
What Happens If NULL Values Are Involved in Expressions? - MySQL FAQs - Introduction to SQL Basics
✍: FYIcenter.com
If NULL values are used in expressions, the resulting values will be NULL values. In other words:
The tutorial exercise shows you some interesting examples:
SELECT NULL + NULL FROM DUAL; NULL SELECT NULL + 7 FROM DUAL; NULL SELECT NULL * 7 FROM DUAL; NULL SELECT NULL = NULL FROM DUAL; NULL SELECT 0 < NULL FROM DUAL; NULL SELECT '' > NULL FROM DUAL; NULL SELECT NULL AND TRUE FROM DUAL; NULL SELECT NULL OR TRUE FROM DUAL; 1 -- This is contradicting against the rules!
2007-05-11, 4996👍, 0💬
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