在PostgreSQL的where子句中访问列别名

Question

我知道我可能需要进行分组才能完成此任务，但我不太了解。PostgreSQL 8.1

我需要将结果集限制为“原始> 2017-01-01”。原始设置在第11行中。它在Excel中作为一列返回，是一个日期。

目前，它返回的结果可以追溯到几年前的数据，而我们并不需要它。

select distribution_stop_information.customer_no,
distribution_line_items.item_number,
distribution_line_items.container_id,
distribution_line_items.item_description,
distribution_stop_information.customer_reference,
distribution_stop_information.bol_number, SUBSTRING(distribution_stop_information.bol_number,1,4) as ODDC,
SUBSTRING(distribution_stop_information.bol_number,9,4) as ODRT,
distribution_stop_information.branch_id,
distribution_stop_information.route_date,
(select count(innerDLI.item_number)-1 from distribution_line_items innerDLI where innerDLI.item_number = distribution_line_items.item_number) as RDLcount,
(select innerDLI.datetime_created from distribution_line_items innerDLI where innerDLI.item_number = distribution_line_items.item_number order by innerDLI.datetime_created asc limit 1) as Origination,
distribution_stop_information.route_code,
distribution_stop_information.stop_name,
distribution_stop_information.stop_address,
distribution_stop_information.stop_city,
distribution_stop_information.stop_state,
distribution_stop_information.stop_zip_postal_code,
distribution_stop_information.stop_signature,
CASE WHEN distribution_line_items.exception_code is not null
    THEN distribution_line_items.exception_code
    ELSE distribution_stop_information.stop_exception_code
    END as ExceptionCode,
distribution_stop_information.signature_file_name,
distribution_stop_information.sign_bitmap_file_exists,
ScanR.item_was_scanned as ScanR,
ScanL.item_was_scanned as ScanL,
ScanD.item_was_scanned as ScanD
from distribution_stop_information
inner join distribution_line_items on distribution_line_items.unique_id_no = distribution_stop_information.unique_id_no
left join distribution_item_scans ScanR on 
    ScanR.item_sequence_no = distribution_line_items.item_sequence_no
    and ScanR.stop_unique_id_no = distribution_stop_information.unique_id_no and ScanR.scan_type = 1
   left join distribution_item_scans ScanL on 
    ScanL.item_sequence_no = distribution_line_items.item_sequence_no
    and ScanL.stop_unique_id_no = distribution_stop_information.unique_id_no and ScanL.scan_type = 2
    and ScanL.scan_datetime between to_date(?, 'YYYY-MM-DD') and ( to_date(?, 'YYYY-MM-DD') + interval '1 day' )
left join distribution_item_scans ScanD on 
    ScanD.item_sequence_no = distribution_line_items.item_sequence_no
    and ScanD.stop_unique_id_no = distribution_stop_information.unique_id_no and ScanD.scan_type = 9
    and ScanD.scan_datetime between to_date(?, 'YYYY-MM-DD') and ( to_date(?, 'YYYY-MM-DD') + interval '1 day' ) 
where
distribution_stop_information.customer_no in ( '90202' )
and distribution_stop_information.route_date between ( to_date(?, 'YYYY-MM-DD') ) and ( to_date(?, 'YYYY-MM-DD') ) 
and distribution_line_items.datetime_created between ( to_date(?, 'YYYY-MM-DD') - interval '288 hours' ) and ( to_date(?, 'YYYY-MM-DD') + interval '12 hours' )

更新：我已将选择内容更改为这样，它似乎正在工作-是否对这样做是否正确有任何想法？它只会一直盯着过去的180天。

(select innerDLI.datetime_created from distribution_line_items innerDLI where innerDLI.item_number = distribution_line_items.item_number and innerDLI.datetime_created > to_date(?, 'YYYY-MM-DD') - interval '180 days'   order by innerDLI.datetime_created asc limit 1) as Origination,

Answer 1

这是您的操作方式-列名中的别名

select 
  -- etc etc 
  (select innerDLI.datetime_created from distribution_line_items innerDLI where innerDLI.item_number = distribution_line_items.item_number order by innerDLI.datetime_created asc limit 1) as Origination,
  -- etc etc
from distribution_stop_information
  -- etc etc

这是将它放在where别名中的方式

select 
  -- etc etc 
  Origination.datetime_created
  -- etc etc
from distribution_stop_information 
left join distribution_line_items AS Origination ON Origination.item_number = distribution_line_items.item_number
where Origination.datetime_created > to_date(?, 'YYYY-MM-DD') - interval '180 days'  
-- etc etc

没有什么比您发布的解决方案 更好 （sql优化器应该产生相同的计划），但是它是“在where子句中使用别名”