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a. The PRICE relation has an attribute named Price. In order to avoid confusion, write SQL query to change the name of the relation
PRICE to COST.
PRICE
UCode Size Price
1 M 500
1 L 580
1 XL 620
2 M 810
2 L 890
2 XL 940
3 M 770
3 L 830
UNIFORM 3 XL 910
4 S 150
UCode UName UColor
1 Shirt White 4 L 170
2 Pant Grey 5 S 180
3 Skirt Grey 5 L 210
4 Tie Blue 6 M 110
5 Socks Blue 6 L 140
6 Belt Blue 6 XL 160
b. M/S Wonderful Garments also keeps handkerchiefs of red color, medium size of '100 each. Insert this record in COST table.
c. When you used the above query to insert data, you were able to enter the values for handkerchief without entering its details in the
UNIFORM relation. Make a provision so that the data can be entered in COST table only if it is already there in UNIFROM table.
d. Further, you should be able to assign a new UCode to an item only if it has a valid UName. Write a query to add appropriate constraint
to the SCHOOL_UNIFORM database.
e. ALTER table to add the constraint that price of an item is always greater than zero.
Ans. a. ALTER TABLE Price
RENAME TO Cost;
b. INSERT INTO Cost
VALUES(7, 'm', 100);
c. ALTER TABLE Cost
ADD FOREIGN KEY(UCode) REFERENCES UNIFORM(UCode);
d. ALTER TABLE Uniform
MODIFY UName VARCHAR(30) NOT NULL;
e. ALTER TABLE Cost
ADD CONSTRAINT CheckPrice
CHECK(Price > 0);
Answers
Multiple Choice Questions
1. (c) 2. (c) 3. (b) 4. (a) 5. (d) 6. (b) 7. (c) 8. (a) 9. (d)
10. (b) 11. (a) 12. (c) 13. (d) 14. (c) 15. (d) 16. (b) 17. (b) 18. (c)
19. (a) 20. (c) 21. (c) 22. (c) 23. (d) 24. (b) 25. (b) 26. (a) 27. (b)
28. (a) 29. (b) 30. (d) 31. (d) 32. (a) 33. (b) 34. (a) 35. (d)
True or False
1. (F) 2. (T) 3. (F) 4. (T) 5. (T) 6. (T) 7. (T) 8. (T) 9. (F)
10. (T) 11. (F) 12. (T) 13. (F) 14. (T)
Fill in the blanks
1. attribute 2. Schema 3. degree 4. relation 5. composite key 6. domain
7. structure 8. domain 9. 1 10. ; (semicolon) 11. DROP TABLE 12. ALTER TABLE
296 Touchpad Informatics Practices-XI

