MySQL - Join & Count rows from another table

Question

I have 3 tables, like:
parent(id, name)
children(id, data, parent_id, timestamp)
table_votes(id, user_id, child_id)

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Answer 1

1) solution with subselect:

SELECT  
    children.id,
    children.data,
    children.parent_id,  
    children.timestamp,  
    (select count(*) from table_votes children.id = table_votes.child_id) as cntVotes
FROM 
  children 
WHERE 
  children.parent_id = 20 
ORDER BY 
  children.timestamp ASC

2) solution with group by:

SELECT  
    children.id,
    children.data,
    children.parent_id,  
    children.timestamp,  
    count(table_votes.id) as cntVotes
FROM 
  children 
LEFT JOIN
  table_votes ON children.id = v.child_id
WHERE 
  children.parent_id = 20 
GROUP BY
    children.id,
    children.data,
    children.parent_id,  
    children.timestamp
ORDER BY 
  children.timestamp ASC