title: Delete n rows of table in mysql database
body: <p>I want to keep my table have max 10 rows of record. I will run cronjob and check if a record exist in my table or not. </p>
  
  <p>So to do that I will insert as many as possible records that aren't exist first, then delete the n numbers of row inserted to keep the row at maximum 10 row.</p>
  
  <p>How do I write my DELETE query? </p>