Database-Management-System
August 29, 2024Database-Management-System
August 29, 2024Database-Management-System
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Question 656
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In RDBMS, the constraint that no key attribute (column) may be NULL is referred to as:
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Referential integrity
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Multi-valued dependency
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Entity Integrity
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Functional dependency
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Question 656 Explanation:
→ The constraint that no key attribute (column) may be NULL is referred to as Entity Integrity.
→ Referential integrity to hold in a relational database, any column in a base table that is declared a foreign key can only contain either null values or values from a parent table’s primary key or a candidate key.
→ A multivalued dependency exists when there are at least three attributes (like X,Y and Z) in a relation and for a value of X there is a well defined set of values of Y and a well defined set of values of Z. However, the set of values of Y is independent of set Z and vice versa.
→ A functional dependency is a constraint between two sets of attributes in a relation from a database. In other words, functional dependency is a constraint that describes the relationship between attributes in a relation.
→ Referential integrity to hold in a relational database, any column in a base table that is declared a foreign key can only contain either null values or values from a parent table’s primary key or a candidate key.
→ A multivalued dependency exists when there are at least three attributes (like X,Y and Z) in a relation and for a value of X there is a well defined set of values of Y and a well defined set of values of Z. However, the set of values of Y is independent of set Z and vice versa.
→ A functional dependency is a constraint between two sets of attributes in a relation from a database. In other words, functional dependency is a constraint that describes the relationship between attributes in a relation.
Correct Answer: C
Question 656 Explanation:
→ The constraint that no key attribute (column) may be NULL is referred to as Entity Integrity.
→ Referential integrity to hold in a relational database, any column in a base table that is declared a foreign key can only contain either null values or values from a parent table’s primary key or a candidate key.
→ A multivalued dependency exists when there are at least three attributes (like X,Y and Z) in a relation and for a value of X there is a well defined set of values of Y and a well defined set of values of Z. However, the set of values of Y is independent of set Z and vice versa.
→ A functional dependency is a constraint between two sets of attributes in a relation from a database. In other words, functional dependency is a constraint that describes the relationship between attributes in a relation.
→ Referential integrity to hold in a relational database, any column in a base table that is declared a foreign key can only contain either null values or values from a parent table’s primary key or a candidate key.
→ A multivalued dependency exists when there are at least three attributes (like X,Y and Z) in a relation and for a value of X there is a well defined set of values of Y and a well defined set of values of Z. However, the set of values of Y is independent of set Z and vice versa.
→ A functional dependency is a constraint between two sets of attributes in a relation from a database. In other words, functional dependency is a constraint that describes the relationship between attributes in a relation.