I have a calculation for Rate chart that goes like this:
Total Number of entries (in a given month)/Cumulative number of records each month
But, both these fields are in two separate tables/data sources without any connection/primary key/link at all.
How do I achieve this calculation without joining these two tables.
If there is no link between the tables then there is no way (in Tableau or any other tool) to do what you want.
However, I suspect that what you mean is slightly different: i'm assuming you mean that there is no well-defined database key that links the fields but there are other things in the tables that are common. Like, for example, the date.
If both table contain a date, then Tableau can use that as a way to blend the two datasources together. You might have to make sure that both tables contain dates in a format that Tableau can interpret. Once you do then you can attach both sources to Tableau and then use the date fields as a way to join the tables together (using the Data: Edit Relationships... menu).
