вычислить итоговый рейтинг !! - calculate overall rating !!

[kashperuk]

I would suggest to simply use a display method.
This way, the employee rating will be available not only after recalculating, but at any point in time during the day.

[mina.mohsen]

@pitersky: The Rating is summary

@kashperuk: I have used display methods before but I want a field to store this data (shown at display method) to reuse it again at other tables.
Can I perform - for example - this equation on fields:
Field Z = Field X + Field Y