MySQL has an IFNULL() function that allows us to easily replace NULL values with another value.
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Oracle ISNULL() Equivalent
Most major DBMSs provide us with a function for replacing null values with another value.
But the name of the function tends to differ across DBMSs. For example, SQL Server has an ISNULL() function, while others (such as MySQL, MariaDB, and SQLite) have an IFNULL() function for doing the same thing.
However, to confuse matters, MySQL and MariaDB each have an ISNULL() function that works differently to SQL Server’s function of the same name (MySQL and MariaDB’s implementation only accept a single argument, and return 1 if its null and 0 if it’s not).
MySQL ISNULL() Explained
In MySQL, the ISNULL() function enables us to check whether a value is null or not. If it’s null, then 1 is returned, otherwise 0 is returned.
How IFNULL() Works in MariaDB
In MariaDB, the IFNULL() function allows us to replace NULL values with another value.
MySQL IF() Function Explained
MySQL has an IF() function that provides a convenient way to perform a simple “IF/ELSE” operation.
It works similar to a basic IF/ELSE statement, in that it allows us to check for a condition, and return a different result depending on whether it’s true or not.
More specifically, if the first argument to the IF() function is true, the second argument is returned. If it’s not true, the third argument is returned.
How COALESCE() Works in MariaDB
In MariaDB, the COALESCE() operator returns the first non-NULL value in the list, or NULL if there are no non-NULL values.
MySQL NULLIF() Explained
In MySQL, NULLIF() is a flow control function that returns NULL if both of its arguments are equivalent. Otherwise it returns the first argument.
JSON_INSERT() vs JSON_SET() vs JSON_REPLACE() in SQLite
SQLite provides several functions for inserting, setting, and replacing values in a JSON document. Specifically, it provides json_insert(), json_set(), and json_replace().
These functions perform similar tasks, and you can sometimes use them interchangeably to a certain point.
But there is definitely a clear difference between each function.
MySQL COALESCE() Explained
In MySQL, the COALESCE() operator returns the first non-NULL value in the list, or NULL if there are no non-NULL values.