how to convert long to int
hi fellas. i was wondering i you could help me. in postgre db i have a field order_time. its data type is int4. there are a couple of records, where order_time is 1536936174. so i have a couple of questions:
1. i was wondering how to set this field value, when im doing insert in my Java code?
2. why the date is stored in a column that has datatype of
int4? why not date or datetime?
3. in java code i see that my entity is private Long orderTime, so does that mean theres a mistake in the code and i need to use Long in the database too? or do i use int in my Java code?
thanks alot11 Replies
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1: Just set the number using
System.currentTimeMillis() / 1000 (and prey they set your server up correctly with timezones etc)
2: Because someone who designed the database didn't know what they were doing, or thought that integers would be "more performant" or some other random reason that isn't really valid
3: use an Integer in your code (or int if it's always mandatory)thanks. now its more clear whats going on. can u elaborate on the ssecond point? why its bad to use unix timestamp?
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Usually it was used when databases didn't have proper support for decent date and time formats
But now timestamp exists in postgres for example why still use it?
Using the correct type limits you or gives you the possibility to do things that make sense for that type
PostgreSQL Documentation
8.5. Date/Time Types
8.5. Date/Time Types # 8.5.1. Date/Time Input 8.5.2. Date/Time Output 8.5.3. Time Zones 8.5.4. Interval Input 8.5.5. Interval Output PostgreSQL supports …
See all the things you can do?
That only make sense on timestamps/dates times etc
oh, i didnt know that
my first reaction was also "there are dedicated datatypes for dates, why use int"
It falls under the general typed programming thing. If you have the type, use it
Like you wouldn't use a string for a uuid
If you use a timestamp in postgres you can use an instant in your Java code
So even more type safety etc etc
thank you
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