In PostgreSQL, maintaining data integrity is essential for reliable database management. Constraints are a primary mechanism for enforcing this integrity, ensuring your data remains consistent and accurate. This article briefly explores key PostgreSQL constraints.

NOT NULL Constraint

Prevents NULL values in specific columns.

CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    email VARCHAR(250) NOT NULL,
    password VARCHAR(250) NOT NULL
);

UNIQUE Constraint

Ensures all entries in a column are distinct.

CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    email TEXT UNIQUE
);

PRIMARY KEY Constraint

Guarantees unique and non-NULL identifiers for records.

CREATE TABLE logs (
    id SERIAL PRIMARY KEY,
    data JSONB
);

FOREIGN KEY Constraint

Maintains referential integrity between related tables.

CREATE TABLE orders (
    id SERIAL PRIMARY KEY,
    customer_id INT NOT NULL REFERENCES customers(id)
);

Conclusion

PostgreSQL constraints are crucial for ensuring data integrity in your database. By enforcing these constraints, you maintain consistency and prevent invalid data entries. For a detailed guide please read Understanding PostgreSQL Data Integrity.