Flink SQL does not support rename after cast type

[徐涛]

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

[Hequn Cheng]

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 <[hidden email]> 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

[徐涛]

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 <[hidden email]> 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 <[hidden email]> 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