Computer Science
Assertion. A unique value that identifies each row uniquely is the primary key.
Reason. Only one column can be made the primary key.
Answer
(c)
Assertion is true but Reason is false.
Explanation
A primary key is a set of one or more attributes (columns) that can uniquely identify tuples within the relation. When a primary key is made up of two or more attributes, it is called as composite primary key. Hence, the reason is false.
Related Questions
Assertion. All types of keys contain unique values for each row.
Reason. A foreign-key attribute of a table is the primary key of another table.
Assertion. The foreign-keys of tables are used to establish relationships with other tables and must be handled carefully.
Reason. Referential integrity is a system of rules that a DBMS uses to ensure that the relationships between tables remain valid and no accidental change or deletion occurs in the related data.
Summarize the major differences between a relation and a traditional file.
Define database.