recently i'm going to connect to PostgreSQL and I need to store date/time in my object to pass to the query for insert and update some table. but there is not clear way in c++ to store and retrieve date/time. any comment?
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2You can covert it to milliseconds from epoch. You might want to look at `chrono` namespace – Fureeish Dec 08 '18 at 23:23
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With what precision was the data stored in the database? if it's +-1 second, well, then a `time_t`willl do. – Ted Lyngmo Dec 09 '18 at 01:16
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PostgreSQL TimeFormat 9+ version https://www.postgresql.org/docs/9.1/datatype-datetime.html
Which is a 8byte int(64 bit) time format in microsecond precision, UTC without timezone (from top of the table).
When you create a table you can either time-stamp the record by PostgreSQL current_timestamp , OR insert into table as integer 64bit microsecond format. since PostgreSQL has multiple time format you should decide time any the format you want from table
PostgreSQL approach CREATE,INSERT,RETRIEVE
"CREATE TABLE example_table(update_time_column TIMESTAMP DEFAULT CURRENT_TIMESTAMP)"
"INSERT INTO example_table(update_time_column) VALUES update_time_column=CURRENT_TIMESTAMP"
"SELECT (EXTRACT(epoch FROM update_time_column)*1000000) FROM example_table"
C++ approach
auto/int64_t cppTime = get64bitMicrosecondFormat from some library`
something similar to this answer: Getting an accurate execution time in C++ (micro seconds)
Then push your object / record to PostGRESQL, when retrieve in microseconds, adjust precision /1000 for milliseconds etc.
Just don't forget to synchronize PostgreSQL and C++ timestamp length (eg. 8byte - 8byte each side) otherwise, your time will be thresholded either side, and you will lose precision / get unexpected time.
Enis Bilgin
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