一个MYSQL语句的疑问

 

我这样写SQL语句：

SELECT PD. * , PA.adname AS adname FROM `propagandize` PD LEFT JOIN `proparaadman` PA ON PD.hiturl = PA.adurl WHERE PD.uid = '30' ORDER BY PD.id DESC LIMIT 0 , 30

出现下面的：

我这样写SQL语句：

SELECT PD. * , PA.adname AS adname FROM `p8_propagandize` PD LEFT JOIN `p8_proparaadman` PA ON PD.hiturl = PA.adurl GROUP BY PD.hiturl HAVING PD.uid = '30' ORDER BY PD.id DESC LIMIT 0 , 30

出现下面的情况：

请问大家这个是什么原因啊？
为什么GROUP BY PD.hiturl后 那些PD.hiturl一样的都合成一条了啊 

解决了 我的解决方法是：

SELECT PD.*,PA.adname AS adname, PA.url AS url FROM `p8_propagandize` PD LEFT JOIN `p8_proparaadman` PA ON PD.hiturl=PA.adurl WHERE PD.uid='30' ORDER BY PD.hiturl DESC