DATABASE SYSTEM CONCEPTS (LOOSELEAF)
7th Edition
ISBN: 9781260515046
Author: SILBERSCHATZ
Publisher: MCG
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Expert Solution & Answer
Chapter 18, Problem 36E
Explanation of Solution
Locking protocol
- Assume that there are two transactions T1 and T2 and two data items A and B.
- Assume that B is high numbered than A.
- Consider the following schedule:
l1(A); w1(A); u1(A); l2(A); r2(A); l2(B); w2(B...
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3. Which of the programs do you currently use the most. Why?
Consider the following database for some store:
Customers (cid, cname, city, discount)Agents (aid, aname, city, percent)Products (pid, pname, city, quantity, price)Orders (ordno, mon, cid, aid, pid, qty, dollars)
The relation Customers records the ID (cid), name (cname), location (city) of each customer and a discount percentage (discount) for this customer.
The relation Agents records the ID (aid), name (aname), location (city) of each agent and a transaction fee (percent) charged by this agent.
The relation Products lists the ID (pid), name (pname), location (city), quantity and price of available products.
And finally, the relation Orders contains a unique order number (ordno), the month (mon), customer (cid), agent (aid), product (pid), quantity (qty) of each order as well as the total value (dollars) of the transaction.
1. Express the following query in SQL
(a) List customers (names) who do not have discounts but purchased at least one product of price greater than $50.
(b) Find…
Consider the following relational schema and briefly answer the questions that follow:
Emp(eid: integer, ename: string, age: integer, salary: real)
Works(eid: integer, did: integer, pct_time: integer)
Dept(did: integer, budget: real, managerid: integer)
a. Define a table constraint on Dept that will ensure that all managers have age > 30.
b. Write SQL statements to delete all information about employees whose salaries exceed that of the manager of one or more departments that they work in. Be sure to ensure that all the relevant integrity constraints are satisfied after your updates.
Chapter 18 Solutions
DATABASE SYSTEM CONCEPTS (LOOSELEAF)
Ch. 18 - Prob. 1PECh. 18 - Prob. 2PECh. 18 - Prob. 3PECh. 18 - Prob. 4PECh. 18 - Prob. 5PECh. 18 - Prob. 6PECh. 18 - Prob. 7PECh. 18 - Prob. 8PECh. 18 - Prob. 9PECh. 18 - Prob. 10PE
Ch. 18 - Prob. 11PECh. 18 - Prob. 12PECh. 18 - Prob. 13PECh. 18 - Prob. 14PECh. 18 - Prob. 17ECh. 18 - Prob. 18ECh. 18 - Prob. 19ECh. 18 - Prob. 20ECh. 18 - Prob. 21ECh. 18 - Prob. 22ECh. 18 - Prob. 23ECh. 18 - Prob. 24ECh. 18 - Prob. 25ECh. 18 - Prob. 26ECh. 18 - Prob. 27ECh. 18 - Prob. 28ECh. 18 - Prob. 29ECh. 18 - Prob. 30ECh. 18 - Prob. 31ECh. 18 - Prob. 32ECh. 18 - Prob. 33ECh. 18 - Prob. 34ECh. 18 - Prob. 35ECh. 18 - Prob. 36E
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