[jira] [Commented] (CALCITE-5248) Support Extended Column Aliasing

["Jay Narale (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-5248?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17613453#comment-17613453 ] 

Jay Narale commented on CALCITE-5248:
-------------------------------------

[https://docs.google.com/document/d/1bt_5CmRg97gh_j_lsVrnoEDn5N3TRNGeYcyX4uGD_0g/edit?usp=sharing]

I have created a few potential edge cases for extended column Aliasing

> 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
>
> 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
> Behavior in Teradata
> Consistent with the above, a Filter is applied to the SubQuery
> 2. When a correlated column outside the query has the same name as the alias
> TBD
>       Here I think the behavior should be identical to the behavior in OrderBy
>  
>  [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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