Instance of the College Database Department ACC Accounting Fiterman (212) 220-81
ID: 3732771 • Letter: I
Question
Instance of the College Database Department ACC Accounting Fiterman (212) 220-8190 CIS Computer Information Systems Fiterman (212) 220-8385 Main (212) 220-1335 Main (212)220-8230 MAT Mathematics NUR Nursing -Department names are unique. - Departments have distinct phone numbers. courseNo deptib ACC122 | ACC Acc ACC241 ACC Federal Taxation CIS395 credits capacity Principles 3 32 30 26 26 30 24 18 CIS Database Systems CIS UNDX MAT20 MAT |Statistics MAT315 MAT Algebra NUR411NUR Surgical Nursing Student studentiD firstName lastName dateofBirth GPA deptiD N012 Roxane Campain 12-MAR-1995 roxane@hotmail com 3.51 NUR C033 Noah Kalafatis 23-JUN-1993 nkalafatis@aol.com 2.36 CIS MO91 Malcolm Tromblay 19-SEP-1991 tromblay@cox.net 3.88 MAT A117 Teddy Pedrozo 16-NOV-1998 tpedrozo@gmail.com 3.69 ACC M148 Irina - Students with the same names do not have the same date of birth. A125 Samira Heintzman 08-IAN-1999 heintz@gmalil.com 374 ACC Garda 02-APR-1997 igarcia @juno. com 335 MAT courseNo semester grade CO33 Cisa95 | Fall 2016 CO33 CIS395 | Fall 2017 A125 |ACC241 |Fall 2016 M091 MAT209Fall 2017 C |MAT315 |Spring 201 A117 M148 MAT209 Fall 2017 M091 |MAT315 |Spring 201 A N012 NUR411 Fall 2016 A117 MAT209 |Spring 2017 D M148 MAT315 Fall 2016Explanation / Answer
True
An attribute is a column of a relation
True
A tuple is a row of a relation
False.
Structure of a relation is its intension whereas extension refers to the data values present in that relation.
False
The number of attributes in the relation is known as degree of the relation.
False
An attribute that uniquely identifies each tuple in a relation is primary key. The foreign key is defined in a second table, but it refers to the primary key in the first table.
True
The presence of duplicates in an instance can be used to show that some attribute combination is not a candidate key.
False
No component of the primary key of a base relation is allowed to accept nulls.
Foreign key can be null.
True
If a table have more than one candidate key, one of them is chosen as primary key from those candidate key. Then the rest of candidate keys are known as an alternate key of that table.
Cardinality is the number of tuples or rows in a table. Hence cardinality of table enrollment is 10.
Degree is the number of attributes in a table. Hence the degree of table student is 7.
A candidate key is a single attribute or the least combination of attributes that uniquely identifies each row in the table. The candidate keys of student table are listed below.
studentID
firstName, lastName
13) The candidate keys of department table are listed below.
deptID
name, building
phoneNO
14)The foreign key is defined in a second table, but it refers to the primary key in the first table. Here foreign keys of enrollment table are
studentID
courseNo
15)An attribute that uniquely identifies each tuple in a relation is primary key. Here primary key of relation of enrollment table are (studentID, courseNo, semester)