SQL display date on fixed frequency - sql

Question

I am trying to create a query which displays dates in a specific interval.For example if I have an hire_date and the min(hire_date) is 2009-01-01 and the max(hire_date) is 2009-03-1, then the table should display hire_date in frequency of 2 days apart. Like:
+---------+
hire_date
+---------+
2009-01-01
2009-01-03
2009-01-05
2009-01-07
..........
The table named Employee_Service contains:
ID Number
Hire_date Timestamp
Name Varchar
The current query that I use is:
select trunc(hire_date) "Date",
count(id) "Num Empl Opened"
from Employee_Service
group by trunc(hire_date)
order by trunc(hire_date)
Is there any way to build a query for this.

Answer 1

You can try:
select trunc(hire_date) "Date",
count(id) "Num Empl Opened"
from Employee_Service
where mod(to_char(hire_date,'dd'),2)<>0
and trunc(hire_date) between to_date('2009-01-01','yyyy-mm-dd') and to_date('2009-03-01','yyyy-mm-dd')
group by trunc(hire_date)
order by trunc(hire_date)

Answer 2

Try this:
WITH DAYS AS
(SELECT TRUNC(TO_DATE('2009-03-01','YYYY-mm-dd')) - ROWNUM*2 D
FROM ALL_OBJECTS
WHERE ROWNUM < 365)
SELECT
DAYS.D
FROM
DAYS WHERE D >= TO_DATE('2009-01-01','YYYY-mm-dd');
Demo

Answer 3

I guess this query like this would help you
select to_date('01/05/2014','DD/MM/YYYY') + level -1 HIRE_DATE
from dual
WHERE MOD(LEVEL,2) <> 0
connect by level <= to_date('01/06/2014','DD/MM/YYYY') - to_date('01/05/2014','DD/MM/YYYY') +1;
WHERE '01/05/2014' is taken as from date and '01/06/2014' is taken as to date.
So your query would be:
IF hire_date is a VARCHAR in DD/MM/YYYY format
select to_date(min(hire_date),'DD/MM/YYYY') + level -1 HIRE_DATE
from dual
WHERE MOD(LEVEL,2) <> 0
connect by level <= to_date(max(hire_date),'DD/MM/YYYY') - to_date(min(hire_date),'DD/MM/YYYY') +1;
Or,
IF HIRE_DATE IS A DATE FIELD,
select (min(hire_date)) + level -1 HIRE_DATE
from dual
WHERE MOD(LEVEL,2) <> 0
connect by level <= (max(hire_date)) - (min(hire_date)) +1;
EDIT:
Max and Min cannot be used with Group by. So use below format:
with cte as
(
select max(hire_date) max_date, min(hire_date) min_date from my_table
where --- all conditions here
and rownum=1
)
select (min_date + level -1) hire_dates
from dual
WHERE MOD(LEVEL,2) <> 0
connect by level <= ( max_date - min_date +1 );
with cte as
(
select max(hire_date) max_date, min(hire_date) min_date from Employee_Service
)
select (min_date + level -1) "Date", count(id) "Num Empl Opened"
from Employee_Service , cte
WHERE MOD(LEVEL,2) <> 0
group by (min_date + level -1)
connect by level <= ( max_date - min_date +1 )
ORDER BY (min_date + level -1);