Coalesce: Learn how to use

Learn how to use the COALESCE function in SQL to return the first non-null value from a list of expressions. See the syntax, an example query, and the result for a table with null values. We covered how to use COALESCE() to replace NULL values, how to compute an alternative value, and how to combine COALESCE() with the ROLLUP clause, among other examples. COALESCE returns the first non-null expr in the expression list. You must specify at least two expressions. If all occurrences of expr evaluate to null, then the function returns null. Oracle Database uses short-circuit evaluation. The database evaluates each expr value and determines whether it is NULL, rather than evaluating all of the expr values before determining whether any of them is NULL. If all occurrences of expr are numeric data type or any nonnumeric data type that can be ... The COALESCE() function simplifies the handling of NULL values in SQL Server by providing a straightforward way to ensure that queries return useful results even when dealing with incomplete or missing data.