Comparing results with today's date?
OK, lets do this properly. Select dates matching today, using indexes if available, with all the different date/time types present.
The principle here is the same in each case. We grab rows where the date column is on or after the most recent midnight (today's date with time 00:00:00), and before the next midnight (tomorrow's date with time 00:00:00, but excluding anything with that exact value).
For pure date types, we can do a simple comparison with today's date.
To keep things nice and fast, we're explicitly avoiding doing any manipulation on the dates stored in the DB (the LHS of the where
clause in all the examples below). This would potentially trigger a full table scan as the date would have to be computed for every comparison. (This behaviour appears to vary by DBMS, YMMV).
MS SQL Server: (SQL Fiddle | db<>fiddle)
First, using DATE
select * from dates
where dte = CAST(CURRENT_TIMESTAMP AS DATE)
;
Now with DATETIME:
select * from datetimes
where dtm >= CAST(CURRENT_TIMESTAMP AS DATE)
and dtm < DATEADD(DD, 1, CAST(CURRENT_TIMESTAMP AS DATE))
;
Lastly with DATETIME2:
select * from datetimes2
where dtm2 >= CAST(CURRENT_TIMESTAMP AS DATE)
and dtm2 < DATEADD(DD, 1, CAST(CURRENT_TIMESTAMP AS DATE))
;
MySQL: (SQL Fiddle | db<>fiddle)
Using DATE:
select * from dates
where dte = cast(now() as date)
;
Using DATETIME:
select * from datetimes
where dtm >= cast((now()) as date)
and dtm < cast((now() + interval 1 day) as date)
;
PostgreSQL: (SQL Fiddle | db<>fiddle)
Using DATE:
select * from dates
where dte = current_date
;
Using TIMESTAMP WITHOUT TIME ZONE:
select * from timestamps
where ts >= 'today'
and ts < 'tomorrow'
;
Oracle: (SQL Fiddle)
Using DATE:
select to_char(dte, 'YYYY-MM-DD HH24:MI:SS') dte
from dates
where dte >= trunc(current_date)
and dte < trunc(current_date) + 1
;
Using TIMESTAMP:
select to_char(ts, 'YYYY-MM-DD HH24:MI:SS') ts
from timestamps
where ts >= trunc(current_date)
and ts < trunc(current_date) + 1
;
SQLite: (SQL Fiddle)
Using date strings:
select * from dates
where dte = (select date('now'))
;
Using date and time strings:
select dtm from datetimes
where dtm >= datetime(date('now'))
and dtm < datetime(date('now', '+1 day'))
;
Using unix timestamps:
select datetime(dtm, 'unixepoch', 'localtime') from datetimes
where dtm >= strftime('%s', date('now'))
and dtm < strftime('%s', date('now', '+1 day'))
;
Backup of SQL Fiddle code
There is no native Now() function in SQL Server so you should use:
select GETDATE() --2012-05-01 10:14:13.403
you can get day, month and year separately by doing:
select DAY(getdate()) --1
select month(getdate()) --5
select year(getdate()) --2012
if you are on sql server 2008, there is the DATE date time which has only the date part, not the time:
select cast (GETDATE() as DATE) --2012-05-01
Not sure what your asking!
However
SELECT GETDATE()
Will get you the current date and time
SELECT DATEADD(dd, 0, DATEDIFF(dd, 0, GETDATE()))
Will get you just the date with time set to 00:00:00