SELECT toStartOfDaytoDateTimeDs AS datetime_day_Ds AppIdentifier AS AppIdentifier -- sumAvgDeviceTime AS index_avgdevicetime_0 CASE WHEN countAvgDeviceTime!=0 1 THEN sumAvgDeviceTimecountAvgDev

这句代码是有语法错误的。在CASE语句中，不可以直接使用count函数来判断条件。正确的写法应该是将count(AvgDeviceTime!=0)作为一个子查询，然后通过别名引用它。以下是修正后的代码：

SELECT toStartOfDay(toDateTime(Ds)) AS datetime_day_Ds, AppIdentifier AS AppIdentifier, CASE WHEN (SELECT count() FROM log_iMonkey_iOS_overview WHERE AvgDeviceTime != 0) > 1 THEN sum(AvgDeviceTime)/(SELECT count() FROM log_iMonkey_iOS_overview WHERE AvgDeviceTime != 0) END AS index_avgdevicetime_0 FROM log_iMonkey_iOS_overview