如何对三个结构数据应用SQL LIMIT？

Question

I use a famous method for showing the three comment from SQL. How I can display only first three root comment with a all sub-comment?

I tried to make something like:

  SELECT * FROM NAMES  ORDER BY pid LIMIT 3 ASC, Id ASC LIMIT 3 

But LIMIT is not supported SQL for each ORDER BY

The example you can see here: http://sqlfiddle.com/#!2/a593d/4

More clear I illustrated in loaded image

Answer 1

The LIMIT keyword in SQL limits the amount of rows that is returned. It there is a sort involved SQL will be smart enough to stop the ordering after the first three rows are found.

If you want to do something else with the LIMIT keyword then you should explain what exactly it is you want to get.

Answer 2

Try below query

  SELECT * 
  FROM NAMES INNER JOIN 
     (SELECT pid 
      FROM NAMES
      GROUP BY pid
      ORDER BY pid
      LIMIT 3) AS my_table 
  USING (pid)

DEMO