Time function support difference, support conversion between string and time format

[kerxyfy]

Support a method: time difference,requirement precision to seconds.
Support a method: add a function of to_datetime, aim to solve String("yyyy-MM-dd HH:mm:ss")) or String("yyyyMMddHHmmss")) become a datetime

[Shylock-Hg]

You can try datetime('yyyy-MM-dd HH:mm:ss')

[Shylock-Hg]

For the time computation, now don't support.

[kerxyfy]

You can try datetime('yyyy-MM-dd HH:mm:ss')

not support 'YYYY-MM-DD HH:mm:ss', own product support 'YYYY-MM-DDThh:mm:ss'.It lead to a time difference with the local time. Is it possible in the next version？

[Shylock-Hg]

You can try datetime('yyyy-MM-dd HH:mm:ss')

not support 'YYYY-MM-DD HH:mm:ss', own product support 'YYYY-MM-DDThh:mm:ss'.It lead to a time difference with the local time. Is it possible in the next version？

Done.

[xiajingchun]

Functions like datediff() to return the days between two dates are highly demanded by customers. Can we add at least datediff() in the coming release?

[Shylock-Hg]

Functions like datediff() to return the days between two dates are highly demanded by customers. Can we add at least datediff() in the coming release?

Please open individual issue

[xiajingchun]

Functions like datediff() to return the days between two dates are highly demanded by customers. Can we add at least datediff() in the coming release?

Please open individual issue

https://github.com/vesoft-inc/requirement-holder/issues/38