php - mysql parent id loop -

i heve 2 mysql tables

participants  id   |   name   | lastname | ----------------------------- 1    |    jon   |   bush   | ----------------------------- 2    |  stephen |   eagle  | 

and

posts  id    |  parentid |  title  |   text -------------------------------------- 1     |    1      |  title1 |  text1 --------------------------------------- 2     |   1       | title3  |  text2 --------------------------------------- 3     |      1    | title4  | text4 -------------------------------------- 4     |      2    |   title |   ttext 

and need out table

-------------------------- id (1) | jon   | title1, title3, title4 ------------------------------ id (2) | stephen | title 

i try with

$result = mysql_query("select name, title, participants.id, parent aposts, participants paricipants.id = parent.parent group last_name  order ......."); 

but in cas cant loop on parent out posts of parent... maybe can me....

i'm not sure if want. seeing example, want return title separated comma every id , name. mysql has builtin function called group_concat concatenate rows instead of columns.

select  a.id, a.name,         group_concat(b.title) titlelist    participants         inner join posts b             on a.id = b.parentid group    a.id, a.name 

• sqlfiddle demo
• mysql group_concat()

output

╔════╦═════════╦══════════════════════╗ ║ id ║  name   ║      titlelist       ║ ╠════╬═════════╬══════════════════════╣ ║  1 ║ jon     ║ title1,title3,title4 ║ ║  2 ║ stephen ║ title                ║ ╚════╩═════════╩══════════════════════╝