求高手指教mySql复杂查询语句

Question

表为流量表：
 reate table PV_ACESS(
id int,  //主键
link_id int, //sum(lin_id计算流量 )
pv_type varchar(4), //分为in(流入)和out（流出）种类型
pv_time datetime
)显示要求如下：  时间           流入量       流出量     
1990-02-01        111           20
1990-02-11        20            50                        条件：<beginTime> 至<endTime>   查询

Answer 1

select pv_time,sum(if(pv_type='in',link_id,0)),sum(if(pv_type='out',link_id,0))
from PV_ACESS
group by pv_time

Answer 2

当您的问题得到解答后请及时结贴.
http://topic.csdn.net/u/20090501/15/7548d251-aec2-4975-a9bf-ca09a5551ba5.html
http://topic.csdn.net/u/20100428/09/BC9E0908-F250-42A6-8765-B50A82FE186A.html
http://topic.csdn.net/u/20100626/09/f35a4763-4b59-49c3-8061-d48fdbc29561.html8、如何给分和结贴？
http://community.csdn.net/Help/HelpCenter.htm#结帖