#     
#  Overview
The `NULLIF` function in **PostgreSQL** is an in-built conditional function that takes two arguments and returns `null` if they equal one another. Otherwise, it returns only the first argument.

The function returns `null` if either of the arguments is `null`. 

#  
## Syntax

```
NULLIF(arg_1, arg_2);
```

The function returns `null` if `arg_1` is equal to `arg_2`, and returns `arg_1` otherwise.

##  
## Example 1


| SQL  | Output  |
| - | - |
| `select nullif(1, 1);`  | `null`  |
| `select nullif(0, 1);`  | `0`  |
| `select nullif('educative', 'edpresso')`  | `educative`  |

CREATE TABLE Product (
    Name 	varchar(100) NOT NULL,
    Price 	int
);

INSERT INTO Product 
    (Name, Price) 
  VALUES ('mobile', 120),
    ('TV', 200),
    ('Remote', NULL),
    ('Laptop', 1000);


select Name, COALESCE(NULLIF(Price, 1000), 0) as new_price from Product;

#   
## Explanation

- Lines 1–3: We define the `Product` table with `Name` and `Price` as attributes.
- Lines 6–11: We insert several records into the `Product` table. Here, we insert a record where `Price` is `null`.
- Line 14: We check whether the price of a product is equal to `1000`. If the price is `1000`, the `NULLIF` function returns `null`. We choose `0` instead of `null` using the [COALESCE](https://www.educative.io/answers/what-is-coalesce-in-postgresql) function.

What is the NULLIF function in PostgreSQL?

The NULLIF function in PostgreSQL returns null if two arguments are equal; otherwise, it returns the first argument.

SQL	Output
`select nullif(1, 1);`	`null`
`select nullif(0, 1);`	`0`
`select nullif('educative', 'edpresso')`	`educative`