How does mysql query the value of id = category id in the same table?

I want to check how many members each user recommended? What members are there?

As shown in the picture

Reply content:

I want to check how many members each user recommended? What members are there?

As shown in the picture

<code>select id,user_name,(select count(1) from user where recommend_id=u.id )recommend_count  from user u</code>

Use aliases to turn this table into two tables and just associate them