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pengzhiwei edited comment on CALCITE-2921 at 3/19/19 12:00 PM: --------------------------------------------------------------- Hi [~julianhyde], I try to make a pr to support null-literal in function call at [https://github.com/apache/calcite/pull/1117]. In this pr,I mapping the SqlTypeName#Null to a specific java class "Null" and allow null-literal matching any input type in the FamilyOperandTypeChecker. I works well in the test case. Can you take a look and give some suggestions ?Thanks! was (Author: pzw2018): Hi [~julianhyde], I try to make a pr to support null-literal in function call at [https://github.com/apache/calcite/pull/1117]. In this pr,I mapping the SqlTypeName#Null to a specific class "Null" and allow null-literal matching any input type in the FamilyOperandTypeChecker. I works well in the test case. Can you take a look and give some suggestions ?Thanks! > nullif(null,y) throws exception in verification > ------------------------------------------------ > > 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: pengzhiwei > Priority: Critical > Labels: pull-request-available > Time Spent: 10m > Remaining Estimate: 0h > > Currently calcite will translate "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! -- This message was sent by Atlassian JIRA (v7.6.3#76005)