What are the common pitfalls to avoid when designing database structures for PHP applications?

One common pitfall to avoid when designing database structures for PHP applications is not normalizing the database properly. This can lead to redundant data, inconsistencies, and difficulties in maintaining and querying the database. To solve this, ensure that your tables are normalized to reduce redundancy and improve data integrity.

CREATE TABLE users (
    id INT PRIMARY KEY,
    username VARCHAR(50) NOT NULL,
    email VARCHAR(100) NOT NULL,
    password VARCHAR(255) NOT NULL
);

CREATE TABLE posts (
    id INT PRIMARY KEY,
    user_id INT,
    title VARCHAR(100) NOT NULL,
    content TEXT NOT NULL,
    FOREIGN KEY (user_id) REFERENCES users(id)
);