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https://issues.apache.org/jira/browse/CALCITE-5248?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17683015#comment-17683015
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Jiajun Xie commented on CALCITE-5248:
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I found a Jira ticket in Spark:
https://issues.apache.org/jira/browse/SPARK-32726
(Maybe we can learn from each other in the future.)
> Support Extended Column Aliasing
> --------------------------------
>
> Key: CALCITE-5248
> URL: https://issues.apache.org/jira/browse/CALCITE-5248
> Project: Calcite
> Issue Type: New Feature
> Reporter: Jay Narale
> Priority: Major
> Labels: pull-request-available
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> Based on the discussion here [1].
> The goal is to support exteneded column aliasing in where , on clause and
> select List. An example is Teradata [2]
> A few edge cases to be considered for proper semantics
> 1. When SubQuery( maybe table) in from and Alias have the same name eg
> {code:java}
> SELECT c_customerId as c FROM ( SELECT c FROM table) WHERE c = 'test' {code}
> {code:java}
> SELECT trim(c_customer_name) as c FROM ( SELECT c FROM table) WHERE c =
> 'test' {code}
> Comments
> In a database, the execution order is *FROM > WHERE > SELECT* so the
> semantics should be that column in the subquery is given priority and a
> filter is applied to that column
>
> Some edge cases that need consideration
> [doc|https://docs.google.com/document/d/1bt_5CmRg97gh_j_lsVrnoEDn5N3TRNGeYcyX4uGD_0g/edit]
>
> [1] - [https://lists.apache.org/thread/7zk5wqgsk64903w5mbt72pwjmsftx0kz]
> [2] -
> [https://docs.teradata.com/r/Teradata-Database-SQL-Fundamentals/June-2017/Basic-SQL-Syntax/Referencing-Object-Names-in-a-Request/Using-a-Column-Alias]
>
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