Extract date (yyyy/mm/dd) from a timestamp in PostgreSQL

Question

I want to extract just the date part from a timestamp in PostgreSQL.

I need it to be a postgresql DATE type so I can insert it into another table that expects a DATE value.

For example, if I have 2011/05/26 09:00:00, I want 2011/05/26

I tried casting, but I only get 2011:

timestamp:date cast(timestamp as date) 

I tried to_char() with to_date():

SELECT to_date(to_char(timestamp, 'YYYY/MM/DD'), 'YYYY/MM/DD')  FROM val3 WHERE id=1; 

I tried to make it a function:

CREATE OR REPLACE FUNCTION testing() RETURNS void AS ' DECLARE i_date DATE; BEGIN     SELECT to_date(to_char(val1, "YYYY/MM/DD"),"YYYY/MM/DD")        INTO i_date FROM exampTable WHERE id=1;     INSERT INTO foo(testd) VALUES (i); END 

What is the best way to extract date (yyyy/mm/dd) from a timestamp in PostgreSQL?

Answer 1

You can cast your timestamp to a date by suffixing it with ::date. Here, in psql, is a timestamp:

# select '2010-01-01 12:00:00'::timestamp;       timestamp       ---------------------  2010-01-01 12:00:00 

Now we'll cast it to a date:

wconrad=# select '2010-01-01 12:00:00'::timestamp::date;     date     ------------  2010-01-01 

On the other hand you can use date_trunc function. The difference between them is that the latter returns the same data type like timestamptz keeping your time zone intact (if you need it).

=> select date_trunc('day', now());        date_trunc ------------------------  2015-12-15 00:00:00+02 (1 row) 

Answer 2

Use the date function:

select date(timestamp_field) from table 

From a character field representation to a date you can use:

select date(substring('2011/05/26 09:00:00' from 1 for 10)); 

Test code:

create table test_table (timestamp_field timestamp); insert into test_table (timestamp_field) values(current_timestamp); select timestamp_field, date(timestamp_field) from test_table; 

Test result: