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From "Victoria Markman (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-2354) Documentation for Concat Function & Concat Operator
Date Fri, 24 Apr 2015 21:12:39 GMT

    [ https://issues.apache.org/jira/browse/DRILL-2354?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14511754#comment-14511754
] 

Victoria Markman commented on DRILL-2354:
-----------------------------------------

Verified in the new version of the docs the following was documented:

{code}
String Concatenate Operator
You can use the following string operators in your Drill queries to concatenate strings:

string || string
string || non-string or non-string || string
The concatenate operator is an alternative to the concat function.

The concat function treats NULL as an empty string. The concatenate operator (||) returns
NULL if any input is NULL.
{code}

> Documentation for Concat Function & Concat Operator 
> ----------------------------------------------------
>
>                 Key: DRILL-2354
>                 URL: https://issues.apache.org/jira/browse/DRILL-2354
>             Project: Apache Drill
>          Issue Type: Improvement
>          Components: Documentation
>            Reporter: Sean Hsuan-Yi Chu
>            Assignee: Kristine Hahn
>
> In Drill, we have two ways to concatenate Strings:
> 1. Concat Function: concat(c1, c2, c3, ...)
> 2. Concat Operator: c1 || c2 || c3 || ...
> They are doing same thing except for dealing with NULL:
> 1. For concat function, NULL is treated as empty string
> 2. For concat operator: if any input is NULL, output NULL (no matter what other columns
are)
> These are subtle difference and would be better to be documented.
> --------------------------------------------------------------------
> Some discussion can be found from DRILL-2328



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