SQL Query : how copy all tags of post into their post content in wordpress by sql query

You can simply preprocess the content by adding a filter to the_content like that:

function wpse_337486( $content ) {

    if ( is_single() ) {

        // Get the current post.
        global $post;

        // Get all post tags. Get only their names.
        $tags = wp_get_post_tags($post->ID, ['fields' => 'names']);

        // Append post tags to content.
        $content = $content . ' ' . implode(' ', $tags);
    }

    return $content;
}

add_filter( 'the_content', 'wpse_337486' );