SQL Best Practices for Data Consistency

When it comes to working with databases, maintaining data consistency is important. Data consistency ensures that the data stored in a database is accurate, reliable, and reflects the true state of the data at any given time. SQL databases operate on the ACID properties (Atomicity, Consistency, Isolation, Durability) to ensure data integrity and consistency. Below are some best practices to follow in SQL to maintain data consistency:

• Constraints such as PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL, and CHECK can be used to ensure that the data entered into a database meets certain criteria, thus ensuring consistency. For example:

CREATE TABLE products (
    product_id INT PRIMARY KEY,
    product_name VARCHAR(255) NOT NULL,
    price DECIMAL(10,2) CHECK (price >= 0)
);

• Transactions allow you to group SQL commands so that if one command in the group fails, all changes made by the other commands are not committed. That is important in maintaining consistency in a database. For example:

BEGIN TRANSACTION;

UPDATE account SET balance = balance - 100 WHERE account_number = '123';
UPDATE account SET balance = balance + 100 WHERE account_number = '456';

COMMIT;

If either of the UPDATE statements fail, the changes will not be saved to the database.