1. Manage external data sources > new > add file 'invoices'
While this is the correct way to link to a table from another file, your design would be simpler if you kept both tables in the same file.
2. Manage > database > relationships. Screen shot attached.
From the screen shot, you have way too many match fields. From what you describe in your post, you should only need to link Invoices to payroll by a single pair of fields, not 5 fields in invoice matched to 5 fields in payroll. What you show makes no sense.
The incorrect relationship will then keep the rest of what you have attempted to set up from working.
What does "factura ID" mean? Does it identify a specific record in Invoices or a specific record in payroll? What I see in your screen shot indicates that it is the Unique ID for each record in Invoices, but if this is not the case, then you have an additional issue with your basic design.
Question: How many records in Invoices should be linked to a given record in Payroll? How many records in Payroll should be linked to a given record in Invoices. What you describe is a "one to one" relationship where there is no more than one record in Invoices linked to no more than one record in Payroll. Are you sure that this is really the case here?
Hi Phil, I've corrected the relationships & it's working perfectly.