CODE EXAMPLE FOR PHP

php add custom button in wordpress editor

add_action( 'manage_post_type_posts_custom_column' , 'my_custom_column', 10, 2 );
function my_custom_column( $column, $post_id ) {
    $my_column_name='NAME-OF-THE-COLUMN';
    switch ( $column ) {
        case $my_column_name:
            echo '<button>My Button</button>';
            break;
    }
}