在mysql查询中加入数据重复之后

Question

table :First
..............................................................................
id | ros | table | column | stool | date | places|
..............................................................................
1   12  5   6   a   2017-07-17  goa  |
2   12  5   6   b   2017-07-17  delhi|
..............................................................................


table :second

..........................................................................
id  | ros | name | email | phone | stos|address |date |
....................................................................................................
5      12    and   [e-mail]  394924673464    6  fddsfds  2017-07-03 |
6      12    her     [e-mail]    84838593894     6  fdafdfd  2017-07-04  |
....................................................................................................


Query like I am Using:
SELECT `p`.* FROM `first` `p` LEFT JOIN `second` as `st` ON `st`.`ros`=`p`.`ros` ORDER BY `id` DESC LIMIT 10;

My question is why it returns 4 rows instead of just 2? its resturning 4 value without having in the table should i need to use distinct or group by for that ??

Answer 1

Try this query :

SELECT p.* FROM first as p LEFT JOIN second as st ON st.site_id=p.site_id group by p.id ORDER BY p.id DESC LIMIT 10;