SQL COALESCE Vs IFNULL Function

The IFNULL() method works in a similar way to COALESCE.

The only difference between the IFNULL() and COALESCE() functions is that the IFNULL() function always takes two parameters, but COALESCE() can take any number of parameters.

When the COALESCE() function has two parameters, it behaves similarly to the IFNULL()function.

SQL COALESCE Function

The COALESCE SQL Server expression takes a list of parameters, evaluates them in order, and returns the first non-null argument.

COALESCE is an expression that can be used in any clause that accepts one, including SELECT , WHERE , GROUP BY , and HAVING.

Example: Implement coalesce function

It is the first non-null argument, the COALESCE expression is used to return the string 'Hi' in the following example:

--sql-server, mysql, sqlite

SELECT COALESCE(NULL, 'Hi', NULL, 'Simmanchith');

Output: The Output of above query is

SQL IFNULL Function

IFNULL() in MySQL takes two expressions and returns the first one if the first one is not Null.

Otherwise, the second expression is returned.

It returns either a numeric or a string value depending on the context in which it is used.

Example: Implement IFNULL Function

In below query we have two values first one is NULL and second one is WEBDESIGN. First value is NULL, Through condition we will get the output of Second value.

--mysql, sqlite

SELECT IFNULL(NULL,'WEBDESIGN');

Output: The result will be,

WEBSEIGN

SQL Difference Between COALESCE And IFNULL Function

There are 4 main contrasts in coalesce vs ifnull function :-

COALESCE	IFNULL
When you have an unknown number of values to check, COALESCE comes in handy.	IFNULL is useful if you have a column that you know can be null but wish to represent with a different value.
The COALESCE function takes n inputs.	With two arguments, the IFNULL function performs admirably.
COALESCE is a function that returns the first non-NULL expression in a list of arguments.	Null values are replaced by the IFNULL function.
The COALESCE() method returns the list's first non-NULL item, or NULL if no non-NULL entries exist.	In MySQL, IFNULL() takes two expressio/ns and returns the first expression if the first expression is not `NULL`, otherwise the second expression.

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