Learn SQL: Primary Key

【SQL】主キー(PRIMARY KEY)制約って何？サンプルコードで基本的な使い方を確認しよう！ | ポテパンスタイル

💡 SQL Interview Question: 👉 How do you add a PRIMARY KEY constraint to an existing table in SQL? This is a frequently asked SQL interview question to test your understanding of constraints and table modification. Here’s the clean SQL query 👇 ALTER TABLE employees ADD CONSTRAINT pk_employees PRIMARY KEY (employee_id); 🎯 Explanation: ALTER TABLE is used to modify an existing table ADD CONSTRAINT defines a new table constraint pk_employees is the name of the primary key constraint employee_id b

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How will you add a primary key to a relation? | Shaalaa.com

Learn SQL: Foreign Key

How to create a SQL Server foreign key

What is a foreign key? (with SQL examples)