What is PostgreSQL equivalent of SYSDATE from Oracle?

Question

I want to perform a query using sysdate like:

select up_time from exam where up_time like sysdate

which is possible in Oracle.

However,

Answer 1

SYSDATE is an Oracle only function.

The ANSI standard defines current_date or current_timestamp which is supported by Postgres and documented in the manual:
http://www.postgresql.org/docs/current/static/functions-datetime.html#FUNCTIONS-DATETIME-CURRENT

(Btw: Oracle supports CURRENT_TIMESTAMP as well)

You should pay attention to the difference between current_timestamp, statement_timestamp() and clock_timestamp() (which is explained in the manual, see the above link)

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This statement:

select up_time from exam where up_time like sysdate

Does not make any sense at all. Neither in Oracle nor in Postgres. If you want to get rows from "today", you need something like:

select up_time 
from exam 
where up_time = current_date

Note that in Oracle you would probably want trunc(up_time) = trunc(sysdate) to get rid of the time part that is always included in Oracle.