Problem

Given the following statement

SELECT CONCAT('TDSMGR',NULL) 

In MariaDB this returns NULL, in Oracle this returns 'TDSMGR'.

In SQL_MODE='Oracle' this different behavior causes significant problems.

Background

CONCAT Function is different implemented.

https://www.techonthenet.com/mariadb/functions/concat.php
https://www.techonthenet.com/oracle/functions/concat.php

Reproduce

See above

Workaround

SELECT CONCAT_WS(', ',

concat_ws('',"TDSMGR",null)

);

or

SELECT CONCAT('TDSMGR',IFNULL(NULL,''));

Solution

For SQL_MODE = 'Oracle' ensure that CONCAT exhibits the Oracle behaviour.