5.4mysql Every derived table must have its own alias

select count(*) as aa from (

select count(*) as sum,addr from t_wifi group by Addr

)

执行报错：[Err] 1248 - Every derived table must have its own alias

解决方法：

select count(*) as aa from (

select count(*) as sum,addr from t_wifi group by Addr

) as tab

参考：http://blog.chinaunix.net/uid-26602509-id-4367383.html

附wifi定位接口：
http://ptool.aliapp.com/getLocationByWifi?wifilist=[{ssid:"V587",bssid:"21c:fa:68:ba:23:a4",latitude:44.036863,lontitude:87.327804},{ssid:"cmeec",bssid:"78:d3:8d:aa:82:9c",latitude:0,lontitude:0}]