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26 wrz 2016 · My understanding is that if @Test is NULL, then it has no value, and is not greater than, less than or even equal to zero. Therefore, testing for NULL is redundant in the above code: IF @Test > 0 -- do something...
14 maj 2021 · SQL Comparison Operators that Work with NULLs. 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.
27 lip 2015 · isnull(name,'') <> :name is shorthand for (name is null or name <> :name) (assuming that :name never contains the empty string, thus why shorthands like this can be bad). Performance-wise, it depends.
The SQL Server ISNULL() function lets you return an alternative value when an expression is NULL: SELECT ProductName, UnitPrice * (UnitsInStock + ISNULL(UnitsOnOrder, 0)) FROM Products;
21 maj 2014 · So basically in SQL Server a NULL means there is no value and thus can't be compared which returns some unexpected results. For example, the following query doesn't return rows where value IS NULL but I want it to: SELECT * FROM table WHERE (value != 26) AND date IS NULL AND last_modified >= '5/21/2014'
3 wrz 2024 · Replaces NULL with the specified replacement value. Transact-SQL syntax conventions. Syntax ISNULL ( check_expression , replacement_value ) Arguments check_expression. The expression to be checked for NULL. check_expression can be of any type. replacement_value. The expression to be returned if check_expression is NULL.
26 wrz 2024 · If the expression is row-valued, then IS NULL is true when the row expression itself is null or when all the row's fields are null, while IS NOT NULL is true when the row expression itself is non-null and all the row's fields are non-null.
