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https://issues.apache.org/jira/browse/CALCITE-3005?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16845093#comment-16845093
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Julian Hyde commented on CALCITE-3005:
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FWIW, the functions are not in Oracle. {{select left('hello', 2) from dual}}
gives {{ORA-00904: "LEFT": invalid identifier}}.
In the doc you have written
{noformat}
{fn LEFT(string, integer)} | Returns the leftmost len characters from the
*string*; Returns NULL if *string* is NULL;{noformat}
but I'd write
{noformat}
{fn LEFT(string, length)} | Returns a substring consisting of the first
*length* characters of *string*{noformat}
Note that I renamed the parameter to *length* make it clearer. And it is
implicit that the result is null if *string* or *length* are null.
> Implement string functions: LEFT, RIGHT
> ---------------------------------------
>
> Key: CALCITE-3005
> URL: https://issues.apache.org/jira/browse/CALCITE-3005
> Project: Calcite
> Issue Type: New Feature
> Reporter: Forward Xu
> Assignee: Forward Xu
> Priority: Major
> Labels: pull-request-available
> Time Spent: 5h 40m
> Remaining Estimate: 0h
>
> Some string functions including LEFT, RIGHT are not implemented now. It would
> be great if these functions can be implemented.
> [{{LEFT(_str_}},_{{len}}_)|https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_left]
> Returns the leftmost _{{len}}_ characters from the string _{{str}}_, or
> {{NULL}} if any argument is {{NULL}}.
> [{{RIGHT(_str_}},_{{len}}_)|https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_right]
> Returns the rightmost _{{len}}_ characters from the string _{{str}}_, or
> {{NULL}} if any argument is {{NULL}}.
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