Data Constraints and Integrity - MySQL

The NOT NULL constraint in MySQL ensures that a column must have a value. It prevents the insertion of NULL values into the specified column.

The UNIQUE constraint in MySQL ensures that each value in a column must be unique. It prevents the insertion of duplicate values into the specified column.

The PRIMARY KEY constraint in MySQL uniquely identifies each row in a table. It ensures that each value in the specified column or set of columns is unique and not NULL.

The FOREIGN KEY constraint in MySQL ensures referential integrity between two tables. It establishes a relationship between a column in one table and the primary key in another table.

The CHECK constraint in MySQL allows you to define custom data validation rules. It checks the value being inserted or updated against a specified condition or expression.

The DEFAULT constraint in MySQL automatically assigns a predefined value to a column if no value is provided during insertion. It ensures that a default value is used when no explicit value is specified.

The PRIMARY KEY constraint in MySQL ensures that a column can have a NULL value or a unique non-NULL value. It allows the uniqueness of values and the presence of NULL as a valid option.

The AUTO_INCREMENT constraint in MySQL allows the creation of an ordered sequence of numeric values for a column. It automatically assigns a unique incrementing value to each new row.

The FOREIGN KEY constraint in MySQL ensures that a column's value references a valid primary key value in another table. It establishes a relationship between two tables based on their key values.