[jira] [Assigned] (CALCITE-2921) Allow NULL as argument to function calls

["Julian Hyde (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-2921?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Julian Hyde reassigned CALCITE-2921:
------------------------------------

    Assignee: Julian Hyde  (was: pengzhiwei)

> Allow NULL as argument to function calls
> ----------------------------------------
>
>                 Key: CALCITE-2921
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2921
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.18.0
>            Reporter: pengzhiwei
>            Assignee: Julian Hyde
>            Priority: Critical
>              Labels: pull-request-available
>          Time Spent: 1h 20m
>  Remaining Estimate: 0h
>
> Currently {{nullif(null,y)}}  throws exception in verification. This is because translates {{nullif(x,y)}} to a case-when expression, just like "case when x = y then null else x". So when "x" is null literal,a exception throws out as follow:
> {code:java}
>  ELSE clause or at least one THEN clause must be non-NULL
> {code}
> I have test in mysql,"nullif(null,y) works well.So I think we should allow this usage of  "nullif".
> There are two ways to fix this issue:
> 1)  Skip the check for "foundNotNull" in SqlCaseOperator#checkOperandTypes:     
> {code:java}
> if (!foundNotNull) {
>   // according to the sql standard we can not have all of the THEN
>   // statements and the ELSE returning null
>   if (throwOnFailure) {
>     throw callBinding.newError(RESOURCE.mustNotNullInElse());
>   }
>   return false;
> }{code}
> However, as the comment says, we cannot have all of the THEN and ELSE returning null.
> 2) Disable the translation from nullif to case-when and keep "nullif" as it is.
> Any suggestion is welcomed,Thanks!



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