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Foreign key is a set of attributes references to primary key or alternative key of same relation or some other relation. Select the correct option regarding the foreign key:
- a)Foreign key not allows NULL values.
- b)Referencing relation record whose foreign key value is NULL is out of referential integrity constraints.
- c)Between referenced and referencing is (1:M) mapping.
- d)Each referenced record can be related to many [0 or more] referencing records and each referencing record can relate to at most 1 referenced records.
Correct answer is option 'B,C,D'. Can you explain this answer?
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Foreign key is a set of attributes references to primary key or altern...
Explanation:
Foreign Key and NULL Values:
- Foreign key allows NULL values in the referencing relation. It is not mandatory to have a value for the foreign key in every record.
Referential Integrity Constraints:
- Referencing a relation record whose foreign key value is NULL does not violate referential integrity constraints. It is valid in the database schema.
Mapping between Referenced and Referencing Records:
- The relationship between referenced and referencing records is typically a (1:M) mapping, where one referenced record can be related to many referencing records.
Relationship Cardinality:
- Each referenced record can be related to many referencing records (0 or more), allowing for flexibility in how data is linked across different tables.
- On the other hand, each referencing record can relate to at most one referenced record, maintaining the integrity of the relationship.
Overall, foreign keys play a crucial role in establishing relationships between different tables in a database, ensuring data consistency and integrity.
Foreign Key and NULL Values:
- Foreign key allows NULL values in the referencing relation. It is not mandatory to have a value for the foreign key in every record.
Referential Integrity Constraints:
- Referencing a relation record whose foreign key value is NULL does not violate referential integrity constraints. It is valid in the database schema.
Mapping between Referenced and Referencing Records:
- The relationship between referenced and referencing records is typically a (1:M) mapping, where one referenced record can be related to many referencing records.
Relationship Cardinality:
- Each referenced record can be related to many referencing records (0 or more), allowing for flexibility in how data is linked across different tables.
- On the other hand, each referencing record can relate to at most one referenced record, maintaining the integrity of the relationship.
Overall, foreign keys play a crucial role in establishing relationships between different tables in a database, ensuring data consistency and integrity.
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Foreign key is a set of attributes references to primary key or altern...
A foreign key is a set of attributes references to the primary key or alternative key of the same relation or some other relation. The correct statement regarding the foreign key is that a referencing relation record whose foreign key value is NULL is out of referential integrity constraints. Between referenced and referencing is (1:M) mapping. Each referenced record can be related to many [0 or more] referencing records and each referencing record can relate to at most 1 referenced records.
Referential integrity is the state of a database in which all values of all foreign keys are valid. A foreign key is a column or a set of columns in a table whose values are required to match at least one primary key or unique key value of a row in its parent table. A referential constraint is a rule that the values of the foreign key are valid only if one of the following conditions is true:
- They appear as values of a parent key.
- Some component of the foreign key is null.
To map (1:M) relationships, the primary key on the `one side' of the relationship is added to the `many sides' as a foreign key.
Hence, the correct options are (B), (C) and (D).
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Foreign key is a set of attributes references to primary key or alternative key of same relation or some other relation. Select the correct option regarding the foreign key:a)Foreign key not allows NULL values.b)Referencing relation record whose foreign key value is NULL is out of referential integrity constraints.c)Between referenced and referencing is (1:M) mapping.d)Each referenced record can be related to many [0 or more] referencing records and each referencing record can relate to at most 1 referenced records.Correct answer is option 'B,C,D'. Can you explain this answer?
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Foreign key is a set of attributes references to primary key or alternative key of same relation or some other relation. Select the correct option regarding the foreign key:a)Foreign key not allows NULL values.b)Referencing relation record whose foreign key value is NULL is out of referential integrity constraints.c)Between referenced and referencing is (1:M) mapping.d)Each referenced record can be related to many [0 or more] referencing records and each referencing record can relate to at most 1 referenced records.Correct answer is option 'B,C,D'. Can you explain this answer? for Computer Science Engineering (CSE) 2024 is part of Computer Science Engineering (CSE) preparation. The Question and answers have been prepared according to the Computer Science Engineering (CSE) exam syllabus. Information about Foreign key is a set of attributes references to primary key or alternative key of same relation or some other relation. Select the correct option regarding the foreign key:a)Foreign key not allows NULL values.b)Referencing relation record whose foreign key value is NULL is out of referential integrity constraints.c)Between referenced and referencing is (1:M) mapping.d)Each referenced record can be related to many [0 or more] referencing records and each referencing record can relate to at most 1 referenced records.Correct answer is option 'B,C,D'. Can you explain this answer? covers all topics & solutions for Computer Science Engineering (CSE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Foreign key is a set of attributes references to primary key or alternative key of same relation or some other relation. Select the correct option regarding the foreign key:a)Foreign key not allows NULL values.b)Referencing relation record whose foreign key value is NULL is out of referential integrity constraints.c)Between referenced and referencing is (1:M) mapping.d)Each referenced record can be related to many [0 or more] referencing records and each referencing record can relate to at most 1 referenced records.Correct answer is option 'B,C,D'. Can you explain this answer?.
Foreign key is a set of attributes references to primary key or alternative key of same relation or some other relation. Select the correct option regarding the foreign key:a)Foreign key not allows NULL values.b)Referencing relation record whose foreign key value is NULL is out of referential integrity constraints.c)Between referenced and referencing is (1:M) mapping.d)Each referenced record can be related to many [0 or more] referencing records and each referencing record can relate to at most 1 referenced records.Correct answer is option 'B,C,D'. Can you explain this answer? for Computer Science Engineering (CSE) 2024 is part of Computer Science Engineering (CSE) preparation. The Question and answers have been prepared according to the Computer Science Engineering (CSE) exam syllabus. Information about Foreign key is a set of attributes references to primary key or alternative key of same relation or some other relation. Select the correct option regarding the foreign key:a)Foreign key not allows NULL values.b)Referencing relation record whose foreign key value is NULL is out of referential integrity constraints.c)Between referenced and referencing is (1:M) mapping.d)Each referenced record can be related to many [0 or more] referencing records and each referencing record can relate to at most 1 referenced records.Correct answer is option 'B,C,D'. Can you explain this answer? covers all topics & solutions for Computer Science Engineering (CSE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Foreign key is a set of attributes references to primary key or alternative key of same relation or some other relation. Select the correct option regarding the foreign key:a)Foreign key not allows NULL values.b)Referencing relation record whose foreign key value is NULL is out of referential integrity constraints.c)Between referenced and referencing is (1:M) mapping.d)Each referenced record can be related to many [0 or more] referencing records and each referencing record can relate to at most 1 referenced records.Correct answer is option 'B,C,D'. Can you explain this answer?.
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