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9 paź 2014 · Note from the docs: When SET ANSI_NULLS is OFF, the Equals (=) and Not Equal To (<>) comparison operators do not follow the ISO standard. A SELECT statement that uses WHERE column_name = NULL returns the rows that have null values in column_name.
28 lut 2014 · To determine whether an expression is NULL, use IS NULL or IS NOT NULL instead of comparison operators, such as = or !=. Comparison operators return UNKNOWN if either or both arguments are NULL.
14 maj 2021 · To handle NULLs correctly, SQL provides two special comparison operators: IS NULL and IS NOT NULL. They return only true or false and are the best practice for incorporating NULL values into your queries.
The MySQL IFNULL() function lets you return an alternative value if an expression is NULL: SELECT ProductName, UnitPrice * (UnitsInStock + IFNULL(UnitsOnOrder, 0)) FROM Products;
14 lut 2012 · The basic difference is that 0 is about measurable quantity, while NULL is about existence. Being a quantity, 0 represents something, i.e. a quantity, that is 0, much like 0.000000001 represents a quantity (one that in problems of every day life is in fact indistinguishably close to 0).
In MySQL, 0 or NULL means false and anything else means true. The default truth value from a boolean operation is 1. NULL instead of death <>. NULL. Two NULL values are regarded as equal in a GROUP BY. When doing an ORDER BY, NULL values are presented first if you do ORDER BY ... ASC and last if you do ORDER BY ...
10 cze 2023 · To check for values that are not NULL, you can use the keyword IS NOT NULL. For example, to find customers that have an email address: SELECT first_name, last_name, email_address FROM customer WHERE email_address IS NOT NULL;
