SQL COALESCE Vs NULLIF Function

The distinction between COALESCE and NULLIF functions will be discussed in this article.

SQL COALESCE Function

In MySQL, the COALESCE() function is used to return the first non-null value in a series of expressions.

This function returns NULL IF all of the list's values are null or if it can't find any non-null values.

You'll learn how to use this function in the SELECT statement to efficiently handle null values.

Example: Execute Coalesec function

--sqlite, mysql,sql-server

SELECT COALESCE('java','python','sql',NULL);

In above query 'java' is first non null value

Output: The result will be

java

Because it is the first non-null entry in the list, when we execute the coalesce function on it.

SQL NULLIF Function

NULLIF() is a MySQL function.The NULLIF function is a control flow function in MySQL that is used to compare two expressions.

It also aids in the prevention of a SQL statement's division by zero error.

The NULLIF function takes two expressions and returns NULL IF the first expression equals the second expression. Otherwise, the first expression is given.

Example 1: In below example return NULL ,IF both expressions are the same..

SELECT NULLIF("javadatabase", "javadatabase");

The MySQL statement in the above function examines whether the first and second expressions are equal. It returns NULL IF both expressions are the same. Otherwise, the first expression will be returned.

Output: The output of Null if have same expression is

NULL

Example 2: In below example returns first expression ,IF both expressions are not same..

SELECT NULLIF("javadatabase", "connection");

In above example we have javadatabase and connection both are different expression so we get first value or expression.

Output: The output of above query is

javadatabase

SQL Difference Between COALESCE And NULLIF Function:-

In below table we discuss the contrast in coalesce & nullif functions:-

COALESCE	NULL IF
This function operates similarly to a "if else" statement in that it accepts several arguments and checks for null values for each. If the first argument is null, it considers the second, and if both the first and second arguments are nulls, it considers the third.	This function is similar to a "if" statement in that it takes two arguments and compares them. If both arguments are the same, the function returns "Null," otherwise the first argument is returned.
It accepts a number of parameters, N. It returns Not Null Values first. Example: `SELECT COALESCE(NULL,2,NULL,3)` Output : 2	It takes two parameters and returns the first if they are not equal. Example:- `SELECT NULLIF(1,2)` Output : 1
The first argument can be Null, but neither of the arguments can be Null.	The first parameter can be Null, but neither of the arguments can be Null.
If both arguments are equal, the first value will be returned. Example: `SELECT COALESCE(2,2)` Output : 2	If both arguments are equal, NULL will be returned. Example: `SELECT NULLIF(2,2)` Output: NULL

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