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22 cze 2007 · Returns a null value if the two specified expressions are equal. NULLIF returns the first expression if the two expressions are not equal. If the expressions are equal, NULLIF returns a null value of the type of the first expression.
3 lis 2009 · To answer the titled question: NULLIF is implemented as a CASE WHEN so it's possible to formulate a CASE WHEN that performs identically in both timing and results. ISNULL however is an intrinsic function.
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 mar 2022 · In this SQL tutorial, we have reviewed the SQL (structured query language) functions COALESCE(), ISNULL(), NULLIF() and how these work in SQL Server, Oracle and PostgreSQL. There are also other ways for checking NULL values such as the IS NULL clause and there are other complex functions in Oracle.
NULLIF is equivalent to a searched CASE expression in which the two expressions are equal and the resulting expression is NULL. We recommend that you not use time-dependent functions, such as RAND(), within a NULLIF function.
The primary difference between your examples is that the latter does not replace NULL with your default value. With regard to performance, you will generally need to try very hard to find a measurable difference (in the order of a few seconds over millions of rows).
29 wrz 2023 · While both ISNULL and NULLIF deal with NULL values, they serve different purposes. ISNULL replaces NULL values, while NULLIF generates NULL values. In conclusion, understanding and utilizing the ISNULL and NULLIF functions can greatly enhance your SQL skills and code efficiency.
