What is the significance of the primary key in a MySQL database and how does it relate to PHP development?

The primary key in a MySQL database uniquely identifies each record in a table. It ensures data integrity and helps optimize query performance. In PHP development, the primary key is often used to retrieve specific records, update data, or establish relationships between tables. 

// Example of creating a table with a primary key in MySQL using PHP
$sql = "CREATE TABLE users (
    id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(30) NOT NULL,
    email VARCHAR(50) NOT NULL
)";

Keywords

primary key MySQL database PHP development data integrity database design

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