CS Professional · Artificial Intelligence, Data Analytics and Cyber Security - Laws and Practice · Database Management
In a relational database table, a column (or set of columns) chosen to uniquely identify each row, which cannot hold NULL values and cannot repeat, is called the:
The primary key is the column or set of columns that uniquely identifies each row in a relation. It cannot contain NULL values or duplicates. A foreign key, by contrast, only references the primary key of another table and may repeat.
- APrimary keyCorrect
- BForeign key
- CAlternate attribute
- DComposite index
Explanation
A primary key uniquely identifies every tuple in a relation and cannot be NULL or duplicated. A foreign key merely refers to a primary key of another table and may repeat or even be NULL.
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