In a recent tutorial, Cloud Guru Amit explains the concept of PRIMARY KEY in Azure SQL Database, a fundamental constraint that ensures each row in a table is uniquely identifiable.
A PRIMARY KEY is a column or set of columns that uniquely identifies each row in a table. It enforces uniqueness and non-null values, making it essential for data integrity and efficient querying. In Azure SQL Database, primary keys are defined at table creation or can be added later using T-SQL commands.
Key points covered include:
- Primary keys must contain unique values and cannot have NULLs.
- A table can have only one primary key, which may consist of single or multiple columns.
- Primary keys automatically create a clustered index by default, though it can be changed to non-clustered.
- Best practices: Choose columns with stable, unique values (e.g., an ID column) and avoid GUIDs for performance reasons.
This tutorial is part of a series for the DP-800 Microsoft SQL Azure Developer certification, helping learners build a strong foundation in database management on Azure.