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https://issues.apache.org/jira/browse/FLINK-6895?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16546071#comment-16546071
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buptljy edited comment on FLINK-6895 at 7/18/18 6:13 AM:
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[~twalthr]
I've submit a PR about this issue. But I find it's difficult to return
different types according to the value of the literal, because we cannot get
the value of the literal in CallGenerator#generate.
Maybe we need another functions called "StrToTime" and "StrToDatetime" ?
[~nssalian] Do you have any good ideas ?
was (Author: wind_ljy):
[~twalthr]
I think we can use "isOperandLiteral" function in SqlOperatorBinding class.
For str_to_date("20-10-2015", "%d-%m-%Y"), the "isOperandLiteral(1, false)"
returns true,
and for str_to_date("20-10-2015", myField), the "isOperandLiteral(1, false)"
return false because myField is an identifier.
And we can do the same judgement in "CallGenerator".
> Add STR_TO_DATE supported in SQL
> --------------------------------
>
> Key: FLINK-6895
> URL: https://issues.apache.org/jira/browse/FLINK-6895
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Affects Versions: 1.4.0
> Reporter: sunjincheng
> Assignee: buptljy
> Priority: Major
> Labels: pull-request-available
>
> STR_TO_DATE(str,format) This is the inverse of the DATE_FORMAT() function. It
> takes a string str and a format string format. STR_TO_DATE() returns a
> DATETIME value if the format string contains both date and time parts, or a
> DATE or TIME value if the string contains only date or time parts. If the
> date, time, or datetime value extracted from str is illegal, STR_TO_DATE()
> returns NULL and produces a warning.
> * Syntax:
> STR_TO_DATE(str,format)
> * Arguments
> **str: -
> **format: -
> * Return Types
> DATAETIME/DATE/TIME
> * Example:
> STR_TO_DATE('01,5,2013','%d,%m,%Y') -> '2013-05-01'
> SELECT STR_TO_DATE('a09:30:17','a%h:%i:%s') -> '09:30:17'
> * See more:
> ** [MySQL|
> https://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_str-to-date]
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