What are the best practices for handling primary keys and unique constraints in PHP MySQL queries?

When working with primary keys and unique constraints in PHP MySQL queries, it is important to ensure that these constraints are properly defined in the database schema to maintain data integrity. To handle primary keys, always specify a column as the primary key when creating a table to uniquely identify each row. For unique constraints, use the UNIQUE keyword when defining a column to ensure that no duplicate values are allowed in that column. 

// Example of creating a table with primary key and unique constraint
$query = "CREATE TABLE users (
    id INT(11) PRIMARY KEY,
    username VARCHAR(50) UNIQUE,
    email VARCHAR(100) UNIQUE
)";
mysqli_query($connection, $query);

Keywords

PHP MySQL primary keys unique constraints queries

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