SQL question challenge (Comments)

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DDL Scripts

CREATE TABLE comments (
  name            varchar(80),
  posts           varchar(80),
  comments         int
 );

 INSERT INTO comments VALUES ('u1', 'page1', '90');
 INSERT INTO comments VALUES ('u1', 'page2', '50');
 INSERT INTO comments VALUES ('u1', 'page3', '40');
 INSERT INTO comments VALUES ('u2', 'page2', '55');
 INSERT INTO comments VALUES ('u2', 'page4', '45');
 INSERT INTO comments VALUES ('u4', 'page4', '30');
 INSERT INTO comments VALUES ('u4', 'page3', '40');
 INSERT INTO comments VALUES ('u3', 'page2', '100');

 Comments I
 name posts comments
 u1 page1 90
 u1 page2 50
 u1 page3 40
 u2 page2 55
 u2 page4 45
 u4 page4 30
 u4 page3 40
 u3 page2 100

QUESTIONS 

1)CALCULATE THE AVERAGE COMMENTS FOR THE USERS WITH >= 2 POSTS, AND EACH POST HAS COMMENTS GREATER OR EQUAL TO 40

# Using join
 select a.name, round(avg(a.comments),2) as avg_comment 
  from comments a 
  join (select name 
     from comments 
     where comments >=40 
     group by name having count(posts) >=2) b 
  on a.name=b.name group by a.name;
 +------+-------------+
 | name | avg_comment |
 +------+-------------+
 | u1   |       60.00 |
 | u2   |       50.00 |
 +------+-------------+

 #Without using join
 select name,
  avg(comments) as avg_count, 
  count(posts) as cnt_posts 
  from comments 
  where comments >= 40  
  group by name having count(posts) >=2;
 +------+-----------+-----------+
 | name | avg_count | cnt_posts |
 +------+-----------+-----------+
 | u1   |   60.0000 |         3 |
 | u2   |   50.0000 |         2 |
 +------+-----------+-----------+
 
 Step by step approach
  1) AVERAGE COMMENTS FOR THE USERS 
  2) WITH >= 2 POSTS, 
  3) AND EACH POST HAS COMMENTS GREATER OR EAUAL TO 40
  
  1)
  select name,round(avg(comments),2) as avg_comments 
   from comments group by name;
   +------+--------------+
   | name | avg_comments |
   +------+--------------+
   | u1   |        60.00 |
   | u2   |        50.00 |
   | u4   |        35.00 |
   | u3   |       100.00 |
  +------+--------------+

  2) 
  select * from comments 
   where comments >=40;
   +------+-------+----------+
   | name | posts | comments |
   +------+-------+----------+
   | u1   | page1 |       90 |
   | u1   | page2 |       50 |
   | u1   | page3 |       40 |
   | u2   | page2 |       55 |
   | u2   | page4 |       45 |
   | u4   | page3 |       40 |
   | u3   | page2 |      100 |
   +------+-------+----------+
  3) 
  select name 
   from comments 
   group by name 
   having count(posts) >=2;
   +------+
   | name |
   +------+
   | u1   |
   | u2   |
   | u4   |
   +------+
  4)
  select name,round(avg(comments),2) as avg_comments 
   from comments 
   where comments >=40 
   group by name 
   having count(posts) >=2;
   +------+--------------+
   | name | avg_comments |
   +------+--------------+
   | u1   |        60.00 |
   | u2   |        50.00 |
   +------+--------------+