python - AWS Unload 语句错误

Question

我尝试运行以下查询以从 Redshift 卸载到 S3，但收到无益的错误。我们尝试转义所有可能导致问题的字符，并传入参数(包装程序是Python):

unload ('select
            user_id
            ,course_id
            ,request_month
            ,user_agent_type
            ,count(session_id)
         from
                (select distinct
                    user_id
                    ,context_id as course_id
                    ,date_trunc(\'month\', request_timestamp) request_month
                    ,session_id
                    ,case
                    when user_agent like \'%CanvasAPI%\' then \'api\'
                    when user_agent like \'%candroid%\' then \'mobile_app_android\'
                    when user_agent like \'%iCanvas%\' then \'mobile_app_ios\'
                    when user_agent like \'%CanvasKit%\' then \'mobile_app_ios\'
                    when user_agent like \'%Windows NT%\' then \'desktop\'
                    when user_agent like \'%MacBook%\' then \'desktop\'
                    when user_agent like \'%iPhone%\' then \'mobile\'
                    when user_agent like \'%iPod Touch%\' then \'mobile\'
                    when user_agent like \'%iPad%\' then \'mobile\'
                    when user_agent like \'%iOS%\' then \'mobile\'
                    when user_agent like \'%CrOS%\' then \'desktop\'
                    when user_agent like \'%Android%\' then \'mobile\'
                    when user_agent like \'%Linux%\' then \'desktop\'
                    when user_agent like \'%Mac OS%\' then \'desktop\'
                    when user_agent like \'%Macintosh%\' then \'desktop\'
                    else \'other_unknown\'
                    end as user_agent_type
                from {}
                where context_type = \'Course\')
                group by
                    user_id
                    ,course_id
                    ,request_month
                    ,user_agent_type')
to {}
credentials 'aws_access_key_id={};aws_secret_access_key={}'
manifest
gzip
delimiter '|'

错误如下:

2016-03-04 14:28:12,208 [CRITICAL] - Error occurred during transaction: syntax error at or near "month"
LINE 12:     ,date_trunc('month', request_timestamp) request_month

Answer 1

request_month 前需要有“as”一词