Steps to reproduce
When executing a query you see an error that looks like this:
Cannot resolve the collation conflict between "SQL_Latin1_X" and "SQL_Latin1_Y" in the concat operation
When you execute the same query directly on your database, it works fine.
The collation of your external DB and your own DB do not match.
If you are using a MSSQL database, Atlassian has an article on how to fix this: https://confluence.atlassian.com/jirakb/how-to-fix-the-collation-of-a-microsoft-sql-server-jira-database-776646810.html
You could also add COLLATE statements to your query, as described here: https://stackoverflow.com/questions/23673096/use-collate-in-concat