Exercise 3 (constraints, 4 pts)

1.Write a CHECK constraint that expresses the following condition on records in table Product in Hardware Database: Maker H produces only printers.

2.Write a CHECK constraint that expresses the following condition on table Schedule in University Database: Each instructor occurring in this table teaches at most three classes per term.

Product

maker	model	type
B	1004	pc
B	1005	pc
B	1006	pc
C	1007	pc
D	1008	pc
D	1009	pc
D	1010	pc
E	1011	pc
E	1012	pc
E	1013	pc
E	2001	laptop
E	2002	laptop
E	2003	laptop
A	2004	laptop
A	2005	laptop
A	2006	laptop
B	2007	laptop
F	2008	laptop
F	2009	laptop
G	2010	laptop
E	3001	printer
E	3002	printer
E	3003	printer
D	3004	printer
D	3005	printer
H	3006	printer
H	3007	printer

Schedule

CourseId	Term	InstrId
CS 200	Fall 2016	003
CS 200	Fall 2017	003
CS 300	Spring 2017	003
CS 400	Fall 2016	004
CS 400	Fall 2017	004
Math 200	Fall 2016	001
Math 200	Spring 2017	004
Math 200	Fall 2017	001
Phys 400	Spring 2017	002