SQL Server Fundamentals: Understanding Primary Keys

Create a Table with a Primary Key

Create a SQL Server table named 'Products' with columns ProductID (primary key), ProductName, and Price.

Expected output: A Products table with ProductID as the primary key.

Hint: Use the PRIMARY KEY constraint on ProductID during table creation.

Add a Primary Key to an Existing Table

Add a primary key constraint to the 'Customers' table on the CustomerID column.

Expected output: CustomerID column in Customers table is set as the primary key.

Hint: Use ALTER TABLE with ADD CONSTRAINT to define the primary key.

Design a Composite Primary Key

Create a table 'Enrollment' with StudentID and CourseID as a composite primary key.

Expected output: Enrollment table with composite primary key on StudentID and CourseID.

Hint: Define PRIMARY KEY (StudentID, CourseID) in the CREATE TABLE statement.

A primary key is a column or set of columns that uniquely identifies each row in a table and enforces uniqueness and non-nullability.

No, primary key columns cannot contain NULL values because they must uniquely identify each record.

A composite primary key consists of two or more columns combined to uniquely identify a record.