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pi Customer.id, Customer.name ( Customer ⨝ | |
( | |
pi id Customer - ( | |
rho id←custid ( | |
pi custid Account | |
) ) | |
) ) |
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-- this is an example | |
group: bankexample | |
Customer = { | |
id:number, name:string, city:string | |
1, 'John', 'Lond' | |
2, Mary, Edin | |
3, Jeff, Lond | |
4, Jane, Card | |
} | |
Account = { | |
number:number, branch:string, custid:number, balance:number | |
111, Lond, 1, 120 | |
222, Edin, 1, 62 | |
333, Lond, 3, 76 | |
444, Lond, 2, 200 | |
} |
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