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https://issues.apache.org/jira/browse/CALCITE-5771?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ZheHu updated CALCITE-5771:
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Summary: Apply two different NULL semantics for CONCAT function(enabled in
MySQL, Postgresql, BigQuery and MSSQL) (was: Apply two different NULL
semantics for CONCAT function(enabled in MySQL、Postgresql、BigQuery and MSSQL))
> Apply two different NULL semantics for CONCAT function(enabled in MySQL,
> Postgresql, BigQuery and MSSQL)
> --------------------------------------------------------------------------------------------------------
>
> Key: CALCITE-5771
> URL: https://issues.apache.org/jira/browse/CALCITE-5771
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.34.0
> Reporter: ZheHu
> Assignee: ZheHu
> Priority: Major
> Labels: pull-request-available
>
> We now have one CONCAT_FUNCTION which is enabled in
> MySQL、Postgresql、BigQuery, it always returns NULL when any of the arguments
> is NULL, and it accepts at least 2 arguments.
> The following table describes how different database products define CONCAT
> function:
> || DB Product || Argument type in CONCAT || Argument num in CONCAT || Result
> ||
> |MySQL|string|at least 1|returns null if any argument is null, otherwise
> return string|
> |BigQuery|string|at least 1|returns null if any argument is null, otherwise
> return string|
> |Postgresql|any(cast to string)|at least 1|always return string, null is
> treated as empty string|
> |MSSQL|string|2 ~ 254|always return string, null is treated as empty string|
> For MySQL and BigQuery, we can reuse the current CONCAT_FUNCTION(but need to
> change the accepted argument number). We also need another CONCAT function
> for Postgresql and MSSQL that treats NULL as empty String. And they both
> accept at least 1 argument.
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