One of the often used functions in SQL Server is ISNULL, which aids in replacing the null values of a column with an alternative value.
The syntax of the ISNULL is provided below:
SELECT ISNULL(expression, alternative_value);
IFNULL is an equivalent function in MySQL.
The definition:
If the expression is NULL, the IFNULL() function returns a specified alternative value. This function returns the expression if it is NOT NULL. This function is typically used to return a different value in the event that a column’s value contains any NULLs.
Syntax:
IFNULL(expression, alternative_value)
Example:
SELECT IFNULL(NULL, “bigdatansql.com”);
Result: bigdatansql.com
Big Data and SQL 