What is a Primary Key in a table?

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Sharp GPT · Answer

In the context of .NET technology and databases a Primary Key in a table is a column or a set of columns that uniquely identifies each row in that table. The primary key constraint ensures that the values in the specified column(s) are unique for every row and that they are not NULL. Here is a concise explanation of the significance of a Primary Key in a table: 1. Uniqueness : A primary key guarantees that each row in the table can be uniquely identified. This means no two rows can have the same value for the primary key column. 2. Indexing : The primary key column(s) are typically indexed which enhances query performance when searching for specific rows based on this key. 3. Relationships : Primary keys play a crucial role in establishing relationships between tables in a database allowing for the implementation of foreign key constraints. In a .NET application defining a primary key is essential for efficient data management and relational database organization. Here's a basic example using SQL Server syntax to create a table with a primary key: CREATE TABLE Employees ( EmployeeID INT PRIMARY KEY FirstName NVARCHAR(50) LastName NVARCHAR(50) ... ); In this example the `EmployeeID` column is designated as the primary key for the `Employees` table. This enforces uniqueness for each employee record based on their ID. Overall understanding and correctly implementing primary keys in tables are fundamental aspects of database design and data integrity particularly when developing applications using .NET technology.