Content DB has been deleted from SQL Server but still get an error 'A SharePoint database named ‘….. ‘ already exists'

This happened to me after I tried to restore few sites with their content databases from CA.  The restoration failed but the content DBs were created in SQL Server but were not displayed in CA.  I simply deleted those databases from SQL Server.  Unfortunately, this caused me not being able to create a new content DB with the same name from CA.  The error message was

• 'A SharePoint database named ‘….. ‘ already exists'

The solution to this problem was to run the following script on the SharePoint_Config database

• Delete FROM Objects WHERE Name = 'name of the ghost db'