hour from timestamp in postgresql for dynamic queries

Question

I have a table named employee with 5 columns. One column is named emp_empdt it's type is timestamp .

I need to get hour value of emp_empdt of every record in the employee table.

I know that, we can get hour by using like

SELECT extract(hour from timestamp '2015-05-02 20:05:12');

This is an static query. But now i need to get timestamp value from employee table.

I used like:

SELECT h1 
from (
   select extract(hour from timestamp emp.emp_empdt) as h1 
   from employee emp
);

for more extract function ->http://stackoverflow.com/a/29839100/3682599 — Vivek S., May 21 '15 at 11:00

score 3 · Accepted Answer · 2015-05-21T09:27:14.453

3

The timestamp keyword is not required:

select extract(hour from emp_empdt) as h1 
from employee emp

The expression timestamp '2015-05-02 20:05:12' is an ANSI SQL timestamp literal and the keyword timestamp is only required for a literal like that. This is necessary to distinguish such an expression from a character literal ('2015-05-02 20:05:12').

edited May 21 '15 at 09:27

answered May 21 '15 at 09:23

@a_horse_with_no_name : Not working while executing above query its say : HINT: No function matches the given name and argument types. You might need to add explicit type casts. – Bhargav Patel Aug 10 '17 at 09:04

hour from timestamp in postgresql for dynamic queries

1 Answers1