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The following demonstrates the behavior of basic arithmetic operators (+,*, etc.):
| operator | Example | Result |
|---|---|---|
| + | date '2001-09-28' + integer '7' | date '2001-10-05' |
| + | date '2001-09-28' + interval '1 hour' | timestamp '2001-09-28 01:00:00' |
| + | date '2001-09-28' + time '03:00' | timestamp '2001-09-28 03:00:00' |
| + | interval '1 day' + interval '1 hour' | interval '1 day 01:00:00' |
| + | timestamp '2001-09-28 01:00' + interval '23 hours' | timestamp '2001-09-29 00:00:00' |
| + | time '01:00' + interval '3 hours' | time '04:00:00' |
| - | - interval '23 hours' | interval '-23:00:00' |
| - | date '2001-10-01' - date '2001-09-28' | integer '3' (days) |
| - | date '2001-10-01' - integer '7' | date '2001-09-24' |
| - | date '2001-09-28' - interval '1 hour' | timestamp '2001-09-27 23:00:00' |
| - | time '05:00' - time '03:00' | interval '02:00:00' |
| - | time '05:00' - interval '2 hours' | time '03:00:00' |
| - | timestamp '2001-09-28 23:00' - interval '23 hours' | timestamp '2001-09-28 00:00:00' |
| - | interval '1 day' - interval '1 hour' | interval '1 day -01:00:00' |
| - | timestamp '2001-09-29 03:00' - timestamp '2001-09-27 12:00' | interval '1 day 15:00:00' |
| * | 900 * interval '1 second' | interval '00:15:00' |
| * | 21 * interval '1 day' | interval '21 days' |
| * | double precision '3.5' * interval '1 hour' | interval '03:30:00' |
| / | interval '1 hour' / double precision '1.5' | interval '00:40:00' |
| Function | Return type | Description | Example | Result |
|---|---|---|---|---|
| age(timestamp, timestamp) | interval | The 'symbolized' result after subtracting the parameter, using years and months, not just days | age(timestamp '2001-04-10', timestamp '1957-06-13') | 43 years 9 mons 27 days |
| age(timestamp) | interval | The result after subtracting the parameter from current_date (at midnight) | age(timestamp '1957-06-13') | 43 years 8 mons 3 days |
| clock_timestamp | timestamp with time zone | The current timestamp of the real-time clock (changes at the time of statement execution)} | ||
| current_date | date | The current date; | ||
| current_time | time with time zone | Current day time; | ||
| current_timestamp | timestamp with time zone | Timestamp when the current transaction begins; | ||
| date_part(text, timestamp) | double precision | Get subdomain (equivalent to extract); | date_part('hour', timestamp '2001-02-16 20:38:40') | 20 |
| date_part(text, interval) | double precision | Get subdomain (equivalent to extract); | date_part('month', interval '2 years 3 months') | 3 |
| date_trunc(text, timestamp) | timestamp | Truncate to the specified precision; | date_trunc('hour', timestamp '2001-02-16 20:38:40') | 2001-02-16 20:00:00 |
| date_trunc(text, interval) | interval | Truncate to the specified precision, | date_trunc('hour', interval '2 days 3 hours 40 minutes') | 2 days 03:00:00 |
| extract(field from timestamp) | double precision | Get subdomain; | extract(hour from timestamp '2001-02-16 20:38:40') | 20 |
| extract(field from interval) | double precision | Get subdomain; | extract(month from interval '2 years 3 months') | 3 |
| isfinite(date) | boolean | Test whether the date is finite (not +/-Infinite) | isfinite(date '2001-02-16') | true |
| isfinite(timestamp) | boolean | Test whether the timestamp is finite (not +/-Infinite) | isfinite(timestamp '2001-02-16 21:28:30') | true |
| isfinite(interval) | boolean | Test whether the time interval is finite | isfinite(interval '4 hours') | true |
| justify_days(interval) | interval | According to each month 30 days adjust the time interval | justify_days(interval '35 days') | 1 mon 5 days |
| justify_hours(interval) | interval | According to each day 24 Adjust the time interval by hours | justify_hours(interval '27 hours') | 1 day 03:00:00 |
| justify_interval(interval) | interval | Adjust the time interval using justify_days and justify_hours while adjusting the sign | justify_interval(interval '1 mon -1 hour') | 29 days 23:00:00 |
| localtime | time | Current day time; | ||
| localtimestamp | timestamp | Timestamp when the current transaction begins; | ||
| make_date(year int, month int, day int) | date | Create a date for the year, month, and day fields | make_date(2013, 7, 15) | 2013-07-15 |
| make_interval(years int DEFAULT 0, months int DEFAULT 0, weeks int DEFAULT 0, days int DEFAULT 0, hours int DEFAULT 0, mins int DEFAULT 0, secs double precision DEFAULT 0.0) | interval | Create an interval from the year, month, week, day, hour, minute, and second fields | make_interval(days := 10) | 10 days |
| make_time(hour int, min int, sec double precision) | time | Create a time from the hour, minute, and second fields | make_time(8, 15, 23.5) | 08:15:23.5 |
| make_timestamp(year int, month int, day int, hour int, min int, sec double precision) | timestamp | Create a timestamp from the year, month, day, hour, minute, and second fields | make_timestamp(2013, 7, 15, 8, 15, 23.5) | 2013-07-15 08:15:23.5 |
| make_timestamptz(year int, month int, day int, hour int, min int, sec double precision, [ timezone text ]) | timestamp with time zone | Create a timestamp with timezone from the year, month, day, hour, minute, and second fields. Use the current timezone if no timezone is specified. | make_timestamptz(2013, 7, 15, 8, 15, 23.5) | 2013-07-15 08:15:23.5+01 |
| now() | timestamp with time zone | Timestamp when the current transaction begins; | ||
| statement_timestamp() | timestamp with time zone | Current timestamp of the real-time clock; | ||
| timeofday() | text | Same as clock_timestamp, but the result is a text String; | ||
| transaction_timestamp() | timestamp with time zone | Timestamp when the current transaction begins; |