>>>Hello,
>>>
>>>How can I make a query in SQL server that involves tables from different databases? I tried MyDB!MyTable, but that does not work.
>>
>>MyDB.dbo.MyTable
>>
>>(Use 3 parts naming convention - DbName.SchemaName.TableName)
>
>So the SchemaName is always "dbo"? or could that be different sometimes?

Could be different, but most likely a dbo. See AdventureWorks sample database, it uses schemas.