What Happens If NULL Values Are Involved In Expressions

What Happens If NULL Values Are Involved In Expressions


  • 25 Dec, 2011

    If NULL values are used in expressions, the resulting values will be NULL values. In other words:► Arithmetic expressions with NULL values result NULL values.► Comparison expressions with NULL values result NULL values.► Logical expressions with NULL values result NULL values.The tutorial exercise shows you some interesting examples:SELECT NULL + NULL FROM DUAL; NULL SELECT NULL + 7 FROM DUAL; NULLSELECT NULL * 7 FROM DUAL; NULLSELECT NULL = NULL FROM DUAL; NULLSELECT 0 < NULL FROM DUAL; NULLSELECT '' > NULL FROM DUAL; NULLSELECT NULL AND TRUE FROM DUAL; NULLSELECT NULL OR TRUE FROM DUAL; 1 -- This is contradicting against the rules!

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