Is there a way to create a date column combining one column having the year as string and one column containing a date-of-year (doy) as integer?
I am aware of methods like SELECT EXTRACT(DOW FROM TIMESTAMP '2001-02-16 20:38:40'); or SELECT to_char(date_trunc('year', now()) + interval '169 days', 'MM/DD') but when trying to replace the "hard coded" stings with the columns I always get some kind of an error.
SELECT s.id, s.year, s.doy,
((s.year||'-01-01')::date + (s.doy||' days')::interval )::date AS date
FROM table_name AS s
the (s.year||'-01-01') or (s.doy||' days') concats the column value with a required string and the ::date or ::interval changes the resulting string type
You can use the make_date() function and add the number of days directly because date + integer is a valid operation:
select make_date(s.year, 1, 1) + s.doy as date
from ...
Related
I m trying to concatenate Date and Time using the below line but i m getting an error. Any help?
Time column type: Time (0)
CONVERT(date, getdate()) + ' ' + CONVERT(time(0), [Time]) AS Date_Time
The data types date and varchar are incompatible in the add operator.
There are a number of ways to do that - one of them is to convert both parts to DateTime which supports the add (+) operator:
SELECT CAST(CAST(GetDate() As Date) As DateTime) + (CAST([Time] As DateTime) As Date_Time
The casting of GetDate() to Date and back to DateTime resets the time portion to midnight.
I use the below and it is working:
CAST(CONVERT(date, getdate()) AS nvarchar) + ' ' + CAST(CONVERT(time(0), [Time]) AS nvarchar) AS Date_Time
Thanks to the rules for data type precedence you are trying to convert ' ' to a data type compatible with date and time, hence the error.
The next problem is that a date does not have a time component, hence to combine the two you need to use a datetime or similar data type.
declare #Time as Time = '12:30:00';
select #Time as Time,
-- Get today's date as a date .
Cast( GetDate() as Date ) as Today,
-- Get today's date and convert it to a datetime so that the time can be added.
Cast( Cast( GetDate() as Date ) as DateTime ) + Cast( #Time as DateTime ) as DateAndTime;
Note that time values need to be converted to datetime (or another compatible type) before adding the values. Curiously, SQL Server 2008 didn't require that step.
date column's format : '2017-03-17'
SELECT EXTRACT(MONTH FROM DATE '2017-03-17') FROM table;
It's giving me 3 instead of March.
extract() returns a number. You want a string, so you can use to_char(<col>, 'Mon'):
select to_char(now(), 'MON')
or for mixed case:
select to_char(now(), 'Mon')
I have a table where column is of datatype timestamp
Which contains records multiple records for a day
I want to select all rows corresponding to day
How do I do it?
Assuming you actually mean timestamp because there is no datetime in Postgres
Cast the timestamp column to a date, that will remove the time part:
select *
from the_table
where the_timestamp_column::date = date '2015-07-15';
This will return all rows from July, 15th.
Note that the above will not use an index on the_timestamp_column. If performance is critical, you need to either create an index on that expression or use a range condition:
select *
from the_table
where the_timestamp_column >= timestamp '2015-07-15 00:00:00'
and the_timestamp_column < timestamp '2015-07-16 00:00:00';
I have a table with two fields:
id(serial), data(jsonb)
And into data I have records with a Datetime field stored as UNIX timestamps:
{"Device":132,"Datetime": 1434166552,...}
I'm trying to query between ranges:
SELECT *
FROM trips
WHERE data->>'Datetime' BETWEEN
EXTRACT(EPOCH FROM date '2014-04-01') AND
EXTRACT(EPOCH FROM date '2014-04-15' + interval '1 day')
AND id = 123
Message
ERROR: operator does not exist: text >= double precision
LINE 3: WHERE data->>'Datetime' BETWEEN
Something I'm doing wrong, please cloud somebody help me? Thanks.
The ->> operator returns an JSON object field as text (see here). You need to cast it :
SELECT *
FROM trips
WHERE (data->>'Datetime')::int
BETWEEN EXTRACT(EPOCH FROM date '2014-04-01')
AND EXTRACT(EPOCH FROM date '2014-04-15' + interval '1 day')
AND id = 123
I got a table:
CREATE TABLE TRANSACTION (
transaction_date date,
id_transaction int,
PRIMARY KEY (id_transaction)
);
and I want to compare the month of 'transaction_date' field with a number of month.
SELECT *
FROM TRANSACTION T
WHERE month = transaction_date;
but I don't know how to make this conversion.
You can use EXTRACT(MONTH FROM transaction_date)
SELECT *
FROM transaction
WHERE EXTRACT(MONTH FROM transaction_date) = 1;
sqlfiddle demo
As per the documentation:
EXTRACT (field FROM source)
The extract function retrieves subfields such as year or hour from
date/time values. source must be a value expression of type timestamp,
time, or interval.
SELECT *
FROM TRANSACTION T
WHERE EXTRACT(MONTH FROM TIMESTAMP transaction_date) = month;
month should be an integer between 1 (January) and 12 (December).