Is there any Cross-platform SQL editors that allow joins from different databases? Initially tried dbeaver but after configuring it, I realized that you can't perform joins from different data bases. 

Also tried TeamSQL which apparently does what I need but looks to be designed without privacy in mind (requires constant connection with internet).

Select a.Product, b.Product, a.ID, b.ID, c.Product, c.ID
FROM SQL_Server 1 a
LEFT JOIN Oracle b
ON a.ID = b.ID
LEFT JOIN SQL Server 2 (another location) c
ON a.ID = c.ID


Thank you for your time.
This seems more like something you'd set up in the database itself, than via an external tool. 

Since this is sql-server, for instance, you can use Linked Servers to accomplish this.