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Реляционная алгебра. Тема 3.2
1.
:2.
:3.
4.
5.
6.
7.
Dn<d1,d1,...dn
-
.
R
8.
-
9.
10.
DriversCOMPANY
DRIVER
11.
COMPANYDRIVER
12.
-13.
14.
815.
IDNAME
COMPANY
PRICE
123
190
156
60
235
100
623
130
16.
Sellers17.
18.
.ID
PRICE
123
190
156
60
235
100
623
130
19.
20.
90.ID
NAME
COMPANY
PRICE
123
190
23
5
100
62
3
130
21.
:ID
NAME
COMPANY
PRICE
123
190
235
100
22.
(PRICE<100 ) PRODUCTSCOMPANY
23.
24.
:PRODUCTS × SELLERS
PRODUCTS.ID
NAME
COMPANY
PRICE
SELLERS.ID
123
190
123
156
60
156
123
190
156
156
60
123
SELLER
25.
PRODUCTS × SELLERSSELLER
26.
ID
27.
PRODUCTS.IDNAME
COMPANY
PRICE
SELLERS.I
D
123
190
123
156
60
156
235
100
235
623
130
623
SELLER
28.
PRODUCTS ⋈ SELLERSPRODUCTS.I
D
NAME
COMPANY
PRICE
SELLER
123
190
OOO
156
60
235
100
623
130