Informatics Practices
Assertion (A): Each table must have one primary key.
Reasoning (R): Primary key is a set of one or more attributes that uniquely identifies a tuple in a relation.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Relational Database
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Answer
Both A and R are true and R is the correct explanation of A.
Explanation
In a database, each table can have only one primary key, which is unique and non-redundant in nature. The primary key is a set of one or more attributes or fields that uniquely identify a tuple or row in a relation.
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Related Questions
Assertion (A): The limitations of traditional file system are overcome by storing data in a database.
Reasoning (R): We can organize related data logically in a database.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): The number of attributes or columns in a relation is called the degree of the relation.
Reasoning (R): The number of tuples or records in a relation is called the cardinality of the relation.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
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Reasoning (R): If a piece of data is stored in two places in a database, then it leads to wastage of storage space.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
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Reasoning (R): Alter table command is used to change the structure of the table.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.