Oracle queries the number of days in a time period

1:oracle Query The total number of messages sent per day for a certain period of time

Select Tab.tday,
(select COUNT (1) from T_msgsendrecode m where trunc (m.sendtime) = To_date (Tab.tday, ' yyyy-mm-dd '))
From (

SELECT * FROM (
Select To_char (Add_months (Last_day (' 2015-6-2 ', ' yyyy-mm-dd ') +1,-1), ' Yyyy-mm-dd ') as Tday from dual
UNION ALL
Select To_char (Add_months (Last_day (' To_date (' 2015-6-2 ', ' yyyy-mm-dd ')) +1,-1) + rownum, ' yyyy-mm-dd ') as Tday
From dual
Connect by RowNum <= (last_day to_date (' 2015-6-2 ', ' yyyy-mm-dd ')-Add_months (Last_day (' 2015-6-2 ', ' Yyyy-mm-dd ')) +1,-1))
)

) tab

2: Query two days of data

Select RowNum dis from (
Select Max (to_date (' 2015-6-30 ', ' Yyyy-mm-dd ')-to_date (' 2015-6-1 ', ' yyyy-mm-dd ') +1 as gap from dual
) Connect by RowNum <= Gap

Oracle queries the number of days in a time period