simple example of a group definition for the relational algebra calculator

gistfile1.txt

group: bank example
description[[ the data for this dataset was generated using <http://www.generatedata.com/>

* the relation _Customers_ contains basic information about the customers of the bank. 
* the relation _Accounts_ contains the basic information of a single account. Note that a customer can have any number of accounts.
* the relation _PremiumCustomers_ contains the customer-ids of all customers with a total balance over 1000
]]


Customers = { cid	firstname	lastname
	1	Dexter	Simpson
	2	Kaseem	Gallagher
	3	Kuame	Hamilton
	4	Robert	Thompson
	5	Rhiannon	Valentine
	6	Calvin	Mays
}
	
Accounts = { 
	aid, cid, balance:number
	1,   1,   66
	2,   1,   -304
	3,   2,   272
	4,   3,   3472
	5,   4,   975.7
	6,   4,   93
	7,   5,   534
	8,   5,   -75.5
}

PremiumCustomers = 
	pi cid (
		sigma sum > 1000 (
			gamma cid; sum(balance)->sum (
				Accounts join Customers
			)
		)
	)