Learn SQL: Primary Key

SQL Server: Primary Key (Khóa chính)

Violation of PRIMARY KEY constraint 'PK_S00T_HangHoa'. Cannot insert duplicate key in object 'dbo.SOOT_HangHoa', lỗi trùng mã hàng

💡 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

Restricciones en SQL Server: SQL NOT NULL, UNIQUE y SQL PRIMARY KEY

Learn SQL: Foreign Key

What is a foreign key? (with SQL examples)

SQL Foreign key