10 Most Important Date / Time related queries
- Get the first day of the month
Quickly returns the first day of current month.
Instead of current month you want to find first day of month where a date
falls, replace SYSDATE with any date column/value.
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SELECT TRUNC (SYSDATE, 'MONTH') "First day of
current month"
FROM DUAL;
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- Get the last day of the month
This query is similar to above but returns last day
of current month. One thing worth noting is that it automatically takes care of
leap year. So if you have 29 days in Feb, it will return 29/2. Also similar to
above query replace SYSDATE with any other date column/value to find last day
of that particular month.
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SELECT TRUNC (LAST_DAY (SYSDATE)) "Last day of
current month"
FROM DUAL;
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- Get the first day of the Year
First day of year is always 1-Jan. This query can
be use in stored procedure where you quickly want first day of year for some
calculation.
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SELECT TRUNC (SYSDATE, 'YEAR') "Year First
Day" FROM DUAL;
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- Get the last day of the year
Similar to above query. Instead of first day this
query returns last day of current year.
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SELECT ADD_MONTHS (TRUNC (SYSDATE, 'YEAR'), 12) - 1
"Year Last Day" FROM DUAL
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- Get number of days in current month
Now this is useful. This query returns number of
days in current month. You can change SYSDATE with any date/value to know
number of days in that month.
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SELECT CAST (TO_CHAR (LAST_DAY (SYSDATE), 'dd') AS INT) number_of_days
FROM DUAL;
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- Get number of days left in current month
Below query calculates number of days left in current
month.
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SELECT SYSDATE,
LAST_DAY
(SYSDATE) "Last",
LAST_DAY
(SYSDATE) - SYSDATE "Days left"
FROM DUAL;
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- Get number of days between two dates
Use this query to get difference between two dates
in number of days.
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SELECT ROUND ( (MONTHS_BETWEEN ('01-Feb-2014',
'01-Mar-2012') * 30), 0)
num_of_days
FROM DUAL;
OR
SELECT TRUNC(sysdate) - TRUNC(e.hire_date) FROM employees;
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Use second query if you need to find number of days
since some specific date. In this example number of days since any employee is
hired.
- Display each months start and end date upto last month of the year
This clever query displays start date and end date
of each month in current year. You might want to use this for certain types of
calculations.
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SELECT ADD_MONTHS (TRUNC (SYSDATE, 'MONTH'), i)
start_date,
TRUNC
(LAST_DAY (ADD_MONTHS (SYSDATE, i))) end_date
FROM XMLTABLE (
'for
$i in 0 to xs:int(D) return $i'
PASSING
XMLELEMENT (
d,
FLOOR
(
MONTHS_BETWEEN
(
ADD_MONTHS
(TRUNC (SYSDATE, 'YEAR') - 1, 12),
SYSDATE)))
COLUMNS
i INTEGER PATH '.');
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- Get number of seconds passed since today (since 00:00 hr)
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SELECT (SYSDATE - TRUNC (SYSDATE)) * 24 * 60 * 60
num_of_sec_since_morning
FROM DUAL;
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- Get number of seconds left today (till 23:59:59 hr)
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SELECT (TRUNC (SYSDATE+1) - SYSDATE) * 24 * 60 * 60
num_of_sec_left
FROM DUAL;
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