A primary key is a concept in database management used to uniquely identify records in a database table. A primary key serves several important functions:
Unique Identification: The primary key ensures that each record in the table has a unique identifier, meaning no two records can have the same primary key value.
Data Integrity: The primary key ensures data integrity by preventing duplicates in the table, thus maintaining the consistency of the database.
Table Relationships: In relational databases, relationships can be established between different tables by using the primary key of one table as a foreign key in another table. This allows for data linking between tables and the execution of complex queries.
A primary key can consist of one or more columns in a table, but in many cases, a single column is used as the primary key. The choice of the primary key depends on the application's requirements and the nature of the database.
Common examples of primary keys include customer or employee IDs in a table, ensuring that each record in that table can be uniquely identified. A primary key can also include automatically generated values like sequential numbers or unique strings.
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