[solved] – Question 94686

Computer (vendor, model, machinetype)
Model (num, speed, ram, hd, price)
Vendor (name, address, phone)
Where vendor indicates the manufacturer of a computer, and machine type takes values such as “desktop”, “laptop” and “server”. Underline indicates the primary key. Following inclusion dependencies hold: vendor ⊆ name, and model ⊆ num. Express following queries in relational algebra:
A. Find all the vendors who make laptop(s).

Expert Answer

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