CS Professional · Artificial Intelligence, Data Analytics and Cyber Security - Laws and Practice · Information Systems
A Mumbai-based retail company stores customer records in a table where each row represents one customer and the column 'CustomerID' uniquely identifies every row. In relational database terminology, what is such a column called?
The column is called a primary key. It uniquely identifies each record in a relational table and cannot hold null values. A foreign key differs because it only references the primary key of another table to link the two tables.
- APrimary keyCorrect
- BForeign key
- CComposite attribute
- DIndex scan
Explanation
A primary key is a column (or set of columns) whose values uniquely identify each row and cannot be null. A foreign key merely refers to the primary key of another table, so it does not itself guarantee uniqueness in its own table.
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