title: Should We Avoid the Use of LEFT JOIN
body: <p>I am confused on an issue from last 7 days. I have googled a lot and also explored SO but could not find satisfactory answer. </p>
  
  <p>I want to clarify my concept on LEFT JOIN. As we Know that LEFT JOIN returns All the Values from the LEFT Table and the Joined Values (through Foreign Keys) From the Right Table. Now, if There are (for example) 10 values in the Right Table pointing to a Primary Key in the LEFT Table, the LEFT JOIN will Repeat the First Table Values 10 Times while giving the Values from the Right Table.  It is just an example. Is it performance effective, OR Should I not be worried about it?</p>
  
  <p>Here is an example of duplicate values</p>
  
  <p><img src="https://i.stack.imgur.com/soHhu.gif" alt="enter image description here"></p>
  
  <p>I have highlighted the duplicate values. 
  Actually, I have a single table and I want to use the LEFT JOIN to get the child comments from the same table. And the Rows could be in 100s not in 1000s. I have indexes on the concerned fields.  So, Please guide me (Keeping in mind the native behavior of LEFT JOIN of giving the Repeated Rows From LEFT Table) that Should I be worried about it? and Is it mostly used or not? </p>