How can the issue of inserting duplicate entries with a constant value of '0' for the primary key field be resolved in the given PHP code?

The issue of inserting duplicate entries with a constant value of '0' for the primary key field can be resolved by checking if a record with the same primary key value already exists before inserting a new record. If a record with the same primary key value exists, then update the existing record instead of inserting a new one. This way, duplicate entries with a constant value of '0' for the primary key field can be avoided. 

// Check if a record with the same primary key value already exists
$query = "SELECT * FROM table_name WHERE primary_key = 0";
$result = mysqli_query($connection, $query);

if(mysqli_num_rows($result) > 0) {
    // Update the existing record
    $update_query = "UPDATE table_name SET column_name = 'new_value' WHERE primary_key = 0";
    mysqli_query($connection, $update_query);
} else {
    // Insert a new record
    $insert_query = "INSERT INTO table_name (primary_key, column_name) VALUES (0, 'new_value')";
    mysqli_query($connection, $insert_query);
}

Keywords

PHP MySQL INSERT IGNORE ON DUPLICATE KEY UPDATE primary key

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