How to insert current_timestamp into Postgres via python
PythonPostgresqlDatetimePython Problem Overview
I need to insert rows into PG one of the fields is date and time with time stamp, this is the time of incident, so I can not use --> current_timestamp function of Postgres at the time of insertion, so how can I then insert the time and date which I collected before into pg row in the same format as it would have been created by current_timestamp at that point in time.
Python Solutions
Solution 1 - Python
A timestamp does not have "a format".
The recommended way to deal with timestamps is to use a PreparedStatement where you just pass a placeholder in the SQL and pass a "real" object through the API of your programming language. As I don't know Python, I don't know if it supports PreparedStatements and how the syntax for that would be.
If you want to put a timestamp literal into your generated SQL, you will need to follow some formatting rules when specifying the value (a literal does have a format).
Ivan's method will work, although I'm not 100% sure if it depends on the configuration of the PostgreSQL server.
A configuration (and language) independent solution to specify a timestamp literal is the ANSI SQL standard:
INSERT INTO some_table
(ts_column)
VALUES
(TIMESTAMP '2011-05-16 15:36:38');
Yes, that's the keyword TIMESTAMP followed by a timestamp formatted in ISO style (the TIMESTAMP keyword defines that format)
The other solution would be to use the to_timestamp() function where you can specify the format of the input literal.
INSERT INTO some_table
(ts_column)
VALUES
(to_timestamp('16-05-2011 15:36:38', 'dd-mm-yyyy hh24:mi:ss'));
Solution 2 - Python
If you use psycopg2 (and possibly some other client library), you can simply pass a Python datetime object as a parameter to a SQL-query:
from datetime import datetime, timezone
dt = datetime.now(timezone.utc)
cur.execute('INSERT INTO mytable (mycol) VALUES (%s)', (dt,))
(This assumes that the timestamp with time zone type is used on the database side.)
More Python types that can be adapted into SQL (and returned as Python objects when a query is executed) are listed here.
Solution 3 - Python
Solution 4 - Python
> Date and time input is accepted in almost any reasonable format, > including ISO 8601, SQL-compatible, traditional POSTGRES, and others. > For some formats, ordering of month, day, and year in date input is > ambiguous and there is support for specifying the expected ordering of > these fields.
In other words: just write anything and it will work.
Or check this table with all the unambiguous formats.
Solution 5 - Python
Sure, just pass a string value for that timestamp column in the format: '2011-05-16 15:36:38' (you can also append a timezone there, like 'PST'). PostgreSQL will automatically convert the string to a timestamp. See http://www.postgresql.org/docs/9.0/static/datatype-datetime.html#DATATYPE-DATETIME-INPUT
Solution 6 - Python
from datetime import datetime as dt
then use this in your code:
cur.execute('INSERT INTO my_table (dt_col) VALUES (%s)', (dt.now(),))
Solution 7 - Python
Just use
> now()
or
> CURRENT_TIMESTAMP
I prefer the latter as I like not having additional parenthesis but thats just personal preference.