Primaarvõtmeid

Primaarvõtmeid, or primary keys, are fundamental concepts in relational database design. A primary key is a column or a set of columns within a table that uniquely identifies each record. This means that no two rows in the table can have the same value or combination of values in the primary key. The primary key is essential for ensuring data integrity and for establishing relationships between different tables.

The purpose of a primary key is to provide a reliable way to access and reference specific data. It acts as a unique address for each row, preventing duplicate entries and allowing for precise data retrieval. When designing a database, selecting an appropriate primary key is crucial. Common choices for primary keys include auto-incrementing integers (often called surrogate keys) or natural keys that are inherently unique within the data itself, such as a social security number or a product ID.

Primary keys also play a vital role in defining relationships between tables through foreign keys. A foreign key in one table references the primary key in another table, linking the two sets of data. This relational capability is a cornerstone of relational databases, enabling complex queries and data manipulation. Without primary keys, maintaining the consistency and accuracy of data across a database would be significantly more challenging.