Constraints in MySQL are rules enforced on data in a table to maintain data integrity and ensure the accuracy of the data. Here's an overview of the different types of constraints:

List of Constraints

• NOT NULL: Ensures that a column cannot have a NULL value.
• UNIQUE: Ensures all values in a column are unique.
• PRIMARY KEY: A combination of NOT NULL and UNIQUE. Uniquely identifies each row in a table.
• FOREIGN KEY: Links two tables together and enforces referential integrity.
• CHECK: Ensures that values in a column meet a specific condition.
• DEFAULT: Provides a default value for a column when no value is specified.

Best Practices

• Use constraints to prevent invalid data from being entered into the database.
• Define primary and foreign keys to ensure data relationships and integrity.
• Be mindful of performance when adding constraints, especially in large tables.

Key Takeaways

• Constraints are essential for maintaining data quality and reliability.
• Different constraints serve different purposes, from enforcing uniqueness to ensuring valid relationships.
• Understanding and using constraints correctly is crucial for database design.