Databases Reference
In-Depth Information
PRODUCT relation
Product
Product
Unit
Number
Name
Price
11
Wrench Model A
12.50
14
Wrench Model B
13.75
17
Wrench Model C
11.62
19
Wrench Model D
15.80
22
Hammer Model A
17.50
24
Hammer Model B
18.00
28
Hammer Model C
19.95
31
Drill Model A
31.25
35
Drill Model B
38.50
43
Deluxe Wrench Set
23.95
44
Master Wrench Set
35.00
48
Deluxe Hammer Set
51.00
FIGURE6.6
General Hardware Company modified
PRODUCT relation
53
Supreme Tool Set
100.00
56
Grand Tool Set
109.95
Assembly
Part
43
11
43
14
44
11
44
17
44
19
48
22
48
24
48
28
53
43
53
48
53
31
56
44
FIGURE6.7
General Hardware Company unary
many-to-many relation
56
48
56
35
11 and 14, as indicated in Figure 6.5. Next, product (assembly) 44 is comprised
of products 11, 17, and 19. Moving to the last three rows of the relation, product
(assembly) 56 is comprised of products 44 and 48, both of which happen to be
assemblies, and product 35. Again, notice the many-to-many relationship as it is
represented in the relation of Figure 6.7. The first two rows indicate that assembly
43
is comprised of
two parts. Conversely, the first and third rows indicate that part
11
is a component of
two different assemblies.
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