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Recent questions tagged referential-integrity

4 votes
4 answers
1
Consider the following statements $S1$ and $S2$ about the relational data model: $S1$: A relation scheme can have at most one foreign key. $S2$: A foreign key in a relation scheme $R$ cannot be used to refer to tuples of $R.$ Which one of the following choices is correct? Both $S1$ and $S2$ are true $S1$ is true and $S2$ is false $S1$ is false and $S2$ is true Both $S1$ and $S2$ are false
asked Feb 18 in Databases Arjun 1.3k views
1 vote
3 answers
2
Following table has two attributes Employee_id and Manager_id, where Employee_id is a primary key and manager_id is a foreign key referencing Employee_id with on-delete cascade: ... $(30, 35)$ and $(35, 20)$ only $(35, 20)$ only $(40, 45)$ and $(25, 40)$ only
asked Jul 2, 2019 in Databases Arjun 1.1k views
1 vote
1 answer
3
How to represent referential integrity constraint in ER model? pls explain with diagram
asked Jun 7, 2019 in Databases aditi19 817 views
0 votes
3 answers
4
The following table has two attributes $X$ and $Y$ where $X$ is the primary key and $Y$ is the foreign key referencing $X$ ... $(4,3)$ and $(6,4)$ $(2,4)$ and $(7,2)$ $(3,2)$ and $(9,5)$ $(3,4), (4,5)$ and $(6,4)$
asked Dec 7, 2018 in Databases Arjun 1.5k views
0 votes
0 answers
5
I've some elementary doubts regarding Foreign keys (referential integrity) : Can a foreign key consist of a collection of attributes - ie. can two or more columns collectively form a foreign key? If foreign key refers to a column within the same ... that has either: Multiple candidate keys Composite candidate keys Overlapping candidate keys If possible, please provide an example. Thank You.!
asked Nov 19, 2018 in Databases Harsh Kumar 369 views
0 votes
0 answers
6
Referencing to this gate ques- https://gateoverflow.in/16095/gate2004_13-let-and-two-relation-schema-where-the-primary-key Let R1 (A, B, C) and R2 (D, E) be two relation schema, where the primary keys are shown underlined, and let C be a foreign key in R1 ... foreign key, subtracting entities of D from C can still have null and other values(those were duplicate). So, how will it get empty set?
asked Sep 1, 2018 in Databases bts1jimin 421 views
0 votes
2 answers
7
Consider the join of a relation R with a relation S. If R has 100 tuples and S has 9 tuples then the maximum and minimum sizes of the join respectively under referential integrity constraint: 9 and 0 9 and 9 9+100 and 0 9*100 and 9
asked Dec 31, 2017 in Databases Priyendu Mori 205 views
1 vote
3 answers
8
select the correct statement from the following on referential integrity Select one: a. referential integrity constraints check whether the primary key, values are unique b. referential integrity constraints check whether an attribute values lies in the ... specified between two relations in a schema d. referential integrity constraints are specified between entities having recursive relationship
asked Dec 17, 2017 in Databases rahul sharma 5 3.4k views
0 votes
1 answer
9
Consider the join of a relation R with a relation S. If R has 100 tuples and S has 9 tuples then the maximum and minimum sizes of the join respectively under referential integrity constraint:- (A) 9 and 0 (B) 9 and 9 (C) 9+100 and 0 (D) 9*100 and 9
asked Dec 16, 2017 in Databases ankitgupta.1729 600 views
1 vote
1 answer
10
Let R (ABCD) and S(DEF). D is the foreign key in R that references primary key in S. Which of the following will not violation? a. Insertion in R b. Insertion in S c. Deletion from R d. Deletion from S
asked Dec 12, 2017 in Databases Mk Utkarsh 177 views
1 vote
1 answer
11
1 vote
1 answer
12
Please help in this question I am getting all of the options as incorrect.Can someone please tell whats the exact answer
asked Jun 9, 2017 in Databases aehkn 752 views
0 votes
1 answer
13
Consider a relation geq which represents "greater than or equal to" that is (x,y) belongs to geq only if y>=x: (create table geq lb integer NOT NULl, ub integer NOT NULL, primary key lb Foreign key (ub) references geq on delete cascade); Which of the following is possible if a tuple (x, ... . b) A tuple (z,w) with z>x is deleted. c) A tuple (z,w) with w<x is deleted. d) the deletion is prohibited.
asked Apr 2, 2017 in Databases Shubhanshu 336 views
46 votes
5 answers
14
Consider the following tables $T1$ and $T2.$ ... cascade. In order to delete record $\langle 3, 8 \rangle$ from the table $T1,$ the number of additional records that need to be deleted from table $T1$ is _______
asked Feb 14, 2017 in Databases Madhav 10.5k views
0 votes
1 answer
15
We can convert any weak entity set to a strong entity set by simply adding appropriate attributes. Why, then, do we have weak entity sets at all? $1)$ We want to avoid the data duplication and consequent possible inconsistencies caused by duplicating the key of the strong entity $2)$ Weak entities reflect the ... reasons from the above: $A)1$ and $2$ $B)2$ and $3$ $C)1$ and $3$ $D)1,2$ and $3$
asked Jan 19, 2017 in Databases Purple 1.1k views
2 votes
2 answers
16
What is on delete no action,on delete cascade, on delete set null action?? explain through some eg??
asked Nov 3, 2016 in Databases Hira Thakur 912 views
5 votes
2 answers
17
1 vote
1 answer
18
____ constraints ensure that a value that appears in one relation for a given set of attributes also appears for a certain set of attributes in another relation. Logical Integrity Referential Integrity Domain Integrity Data Integrity
asked Jul 23, 2016 in Databases jothee 3k views
2 votes
2 answers
19
Purpose of 'Foreign Key' in a table is to ensure Null Integrity Referential Integrity Domain Integrity Null and Domain Integrity
asked May 30, 2016 in Databases Anuanu 2.3k views
0 votes
0 answers
20
Consider the LIBRARY relational database schema shown in the figure below .Choose the appropriate action (reject, cascade, set to NULL, set to default) for each referential integrity constraint, both for the deletion of a referenced tuple and for the update of primary key attribute value in a referenced tuple.Justify your choices
asked Apr 2, 2016 in Databases ibia 479 views
0 votes
0 answers
21
Consider the database shown below ,Whose schema is also shown below .What are the referential integrity constraints that should hold on the schema ? Write appropriate $SQL$ $DDL$ statements ... Course_number Credit_hours Department PREREQUISITE Course_number Prerequisite_number SECTION Section_identifier Course_number Semester year Instructor GRADE_REPORT Student_number Section_identifier Grade
asked Apr 1, 2016 in Databases ibia 208 views
0 votes
1 answer
22
what is the advantage of keeping the Foreign Key null as we know if we make the Foreign Key null we cant reference it again so thats a disadvantage ......so there must be some advantage which outweighs this disadvantage so whats that advantage
asked Feb 3, 2016 in Databases Bhagirathi 203 views
1 vote
3 answers
23
0 votes
3 answers
24
R(ABC)     S(BDE) F:A->B      B ->C     B->D     D->E AND R HAS 100 TUPLES AND S HAS 200
asked Aug 17, 2015 in Databases uzumzki 1.4k views
25 votes
2 answers
25
Let $R (a, b, c)$ and $S(d, e, f)$ be two relations in which $d$ is the foreign key of $S$ that refers to the primary key of $R$. Consider the following four operations $R$ and $S$ Insert into $R$ Insert into $S$ Delete from $R$ Delete from $S$ Which of the following can cause violation of the referential integrity constraint above? Both I and IV Both II and III All of these None of these
asked Sep 29, 2014 in Databases Kathleen 7k views
31 votes
2 answers
26
The following table has two attributes $A$ and $C$ where $A$ is the primary key and $C$ is the foreign key referencing $A$ ... $(5, 2)$ and $(7, 2)$ $(5, 2), (7, 2)$ and $(9, 5)$ $(3, 4), (4, 3)$ and $(6, 4)$
asked Sep 22, 2014 in Databases Kathleen 8.9k views
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