How to write timestamp to txt file when milliseconds are zeroes in python

I’m extracting create timestamp from DB/2 table and writing it to a txt file to be used in later processing. Python writes the timestamp correctly except when the milliseconds are zeroes. When the milliseconds are zeroes, it does not write the milliseconds. How can I make it write the zero milliseconds?

import ibm_db
import datetime

sql = ("SELECT CRT_TS FROM TABLE_TIMEST WHERE DATE(CRT_TS) > '2018-01-01' WITH UR;")
stmt = ibm_db_exec_immediate(conn,sql)
fle = open("c:Testtstamps.txt","w+")
dictionary = ibm_db.fetch_both(stmt)
while dictionary != False

    fle.write(str(dictionary["CRT_TS"]))
    dictionary = ibm_db.fetch_both(stmt)

fle.close()

The timestamps on the table are:

2018-06-12 18:50:55.125489
2018-06-12 18:57:52.000000
2018-06-12 18:58:42.152469

I expect to get the same in my output file, instead I get:

2018-06-12 18:50:55.125489
2018-06-12 18:57:52
2018-06-12 18:58:42.152469

How do I get python to write the zeroes in the milliseconds?

Answer

Your timestamps seem to already be datetime objects, so you just use their own strftime method:

fle.write(dictionary["CRT_TS"].strftime('%Y-%m-%d %H:%M:%S.%f'))