一个select 块里面只能支持一个transform？

完整的官方说明见 https://help.aliyun.com/document_detail/73719.html

从官方说明的句法定义看，应该是一个SELECT块里面是可以嵌套使用的。

SELECT TRANSFORM(key, value) USING 'cmd2' from 
(
    SELECT TRANSFORM(*) USINg 'cmd1' from 
    (
        SELECt * FROM data distribute by col2 sort by col1
    ) t distribute by key sort by value
) t2;

官方文档说明见: https://help.aliyun.com/document_detail/73719.html

从文档中可以看出，是允许嵌套的。

SELECT TRANSFORM(key, value) USING 'cmd2' from 
(
    SELECT TRANSFORM(*) USINg 'cmd1' from 
    (
        SELECt * FROM data distribute by col2 sort by col1
    ) t distribute by key sort by value
) t2;

官方文档说明见: https://help.aliyun.com/document_detail/73719.html

从文档中可以看出，是允许嵌套的。

SELECT TRANSFORM(key, value) USING 'cmd2' from 
(
    SELECT TRANSFORM(*) USINg 'cmd1' from 
    (
        SELECt * FROM data distribute by col2 sort by col1
    ) t distribute by key sort by value
) t2;