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Posted to user@flink.apache.org by 徐涛 <ha...@gmail.com> on 2018/08/14 04:51:22 UTC

Flink SQL does not support rename after cast type

Hi All,
	I am working on a project based on Flink SQL, but found that I can`t rename column after casting, the code is as below:
	cast(json_type as INTEGER) as xxx
	
	And the following exception is reported:
	org.apache.calcite.runtime.CalciteContextException: From line 4, column 6 to line 11, column 38: Illegal mixing of types in CASE or COALESCE statement

	I want to know that does Flink do not support this function because I think it is a common case? Is there a way to accomplish this function?
	Thank a lot.

Best
Henry Xu

Re: Flink SQL does not support rename after cast type

Posted by 徐涛 <ha...@gmail.com>.

Hi Hequn,
	Thanks a lot for your anwswer! The question is clear now.

Best
Henry

> 在 2018年8月14日，下午1:24，Hequn Cheng <chenghequn@gmail.com <ma...@gmail.com>> 写道：
> 
> Hi Henry,
> 
> Flink does support rename column after casting.
> 
> The exception is not caused by cast. It is caused by mixing of types, for example,  the query 
> "CASE 1 WHEN 1 THEN true WHEN 2 THEN 'string' ELSE NULL END"
> will throw the same exception since type of true and 'string' are not same.
> 
> Best, Hequn.
> 
> On Tue, Aug 14, 2018 at 12:51 PM, 徐涛 <happydexutao@gmail.com <ma...@gmail.com>> wrote:
> Hi All,
>         I am working on a project based on Flink SQL, but found that I can`t rename column after casting, the code is as below:
>         cast(json_type as INTEGER) as xxx
> 
>         And the following exception is reported:
>         org.apache.calcite.runtime.CalciteContextException: From line 4, column 6 to line 11, column 38: Illegal mixing of types in CASE or COALESCE statement
> 
>         I want to know that does Flink do not support this function because I think it is a common case? Is there a way to accomplish this function?
>         Thank a lot.
> 
> Best
> Henry Xu
>

Re: Flink SQL does not support rename after cast type

Posted by Hequn Cheng <ch...@gmail.com>.

Hi Henry,

Flink does support rename column after casting.

The exception is not caused by cast. It is caused by mixing of types, for
example,  the query

> "CASE 1 WHEN 1 THEN *true* WHEN 2 THEN *'string'* ELSE NULL END"

will throw the same exception since type of true and 'string' are not same.

Best, Hequn.

On Tue, Aug 14, 2018 at 12:51 PM, 徐涛 <ha...@gmail.com> wrote:

> Hi All,
>         I am working on a project based on Flink SQL, but found that I
> can`t rename column after casting, the code is as below:
>         cast(json_type as INTEGER) as xxx
>
>         And the following exception is reported:
>         org.apache.calcite.runtime.CalciteContextException: From line 4,
> column 6 to line 11, column 38: Illegal mixing of types in CASE or COALESCE
> statement
>
>         I want to know that does Flink do not support this function
> because I think it is a common case? Is there a way to accomplish this
> function?
>         Thank a lot.
>
> Best
> Henry Xu