[jira] [Commented] (CALCITE-759) Add DayOfWeek and other missing date/time functions

["Sergey Nuyanzin (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-759?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16490251#comment-16490251 ] 

Sergey Nuyanzin commented on CALCITE-759:
-----------------------------------------

Hello everyone
if nobody minds I can proceed here as I already did some work within https://issues.apache.org/jira/browse/CALCITE-2303. As far as I see from current doc and code {quote}Useful MySQL functions: DAYOFWEEK, DAYOFMONTH, DAYOFYEAR, QUARTER{quote} are already implemented, a part of {quote}Postgres supports extra time-units in EXTRACT: CENTURY, DECADE, DOW, DOY, EPOCH, ISODOW, ISOYEAR, MICROSECONDS, MILLENNIUM (see http://www.postgresql.org/docs/9.1/static/functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT).{quote} are also already implemented the other part  of EXTRACT  is covered in https://issues.apache.org/jira/browse/CALCITE-2303.

To summarize what is not done
# TO_CHAR(datetime, text) and TO_CHAR(interval, text).
# CONVERT and DATEDIFF.
# TO_TIMESTAMP (string date, [string pattern]) 


> Add DayOfWeek and other missing date/time functions
> ---------------------------------------------------
>
>                 Key: CALCITE-759
>                 URL: https://issues.apache.org/jira/browse/CALCITE-759
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: Julian Hyde
>            Assignee: Julian Hyde
>            Priority: Major
>              Labels: dialect, newbie
>
> Calcite implements EXTRACT, FLOOR, CEIL, CAST, +, - on date/time values and much can be accomplished with these. But there are other useful functions in other databases.
> For example MySQL has DayOfWeek. See https://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html. It is tricky to achieve the same in Calcite (you'd need to subtract the epoch and take the interval modulo 7).
> We need to review the date/time functions in MySQL, Postgres and Oracle, and add functions to ensure that you can accomplish the same things in Calcite fairly easily.



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