query with join across multiple databases-syntax error

Question

I have 2 databases namely db1,db2. I need a query that fetch the data from these dbs(db1,db2) which have inturn 2 tables(concessions,invoicing) each.

In db1.concessions

Answer 1

You can reference other databases directly if the user has permissions.

..

Is the full "path" to the database table.

Often you use

db1.dbo.tbl1 join db2.dbo.tbl2

where dbo is default for database owner, any table not owned by a specific user is owned by dbo by default.

UPDATE

To get the query to validate you can expand it to this

SELECT * FROM 
(SELECT a.concession as db1_CON_NUMBER FROM db1.dbo.concessions as a  
UNION 
SELECT b.[Concession Number] as db1_CON_NUMBER FROM db1.dbo.invoicing as b ) c

INNER JOIN 

(SELECT c.concession as db2_CON_NUMBER FROM db2.dbo.concessions as a 
UNION 
SELECT b.[Concession Number] as db2_CON_NUMBER FROM db2.dbo.invoicing as b ) d

ON db1_CON_NUMBER = db2_CON_NUMBER 

But I have not had time to check if this would return the right data but you can test.