What is coalesce in SQL Server with example?

For example, as we know, the Coalesce function returns the first non-NULL values. SELECT COALESCE (expression1, expression2, expression3) FROM TABLENAME; The above Coalesce SQL statement can be rewritten using the CASE statement. The query returns the same result as the one that uses the COALESCE function.

What does coalesce function do in SQL?

The COALESCE function returns the first non-NULL value from a series of expressions. The expressions are evaluated in the order in which they are specified, and the result of the function is the first value that is not null. The result of the COALESCE function returns NULL only if all the arguments are null.

What is a characteristic of the coalesce function?

The COALESCE function evaluates its arguments from left to right. It stops evaluating until it finds the first non-NULL argument. It means that all the remaining arguments are not evaluated at all. The COALESCE function returns NULL if all arguments are NULL .

What does coalesce mean in SQL?

COALESCE function in SQL Server. 1. The COALESCE function in SQL server is used to return the first Non-NULL value from the list of columns/arguments given in order. 2. COALESCE is considered similar to writing a CASE statement expression in SQL. 3. COALESCE is an ANSI SQL standard function. It is available with all major RDBMS including Oracle, MySQL.

How does coalesce work SQL?

SQL Coalesce function. The SQL Coalesce and IsNull functions are used to handle NULL values. During the expression evaluation process the NULL values are replaced with the user-defined value. The SQL Coalesce function evaluates the arguments in order and always returns first non-null value from the defined argument list.

What is a function in SQL?

A function is a database object in SQL Server. Basically, it is a set of SQL statements that accept only input parameters, perform actions and return the result.