dongpo3957 2013-06-13 08:07 采纳率: 0%
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如何在第一个查询中创建已经LEFT JOIN的子查询

Good Day I would like t ask if what seem to be the problem with my SQL command?? the error I've got was #1054 - Unknown column 'imaster_tbl.id' in 'field list'

i think it is because I put 't1' after imaster_tbl after the FROM keyword

can you please help me with this problem.. here's my SQL Command:

    SELECT imaster_tbl.id, imaster_tbl.die_name, imaster_tbl.part_name,
imaster_tbl.drawing_number, imaster_tbl.drawing_part_number,
imaster_tbl.sub_letter,imaster_tbl.specs, imaster_tbl.file_path,
idrawing_type_tbl.drawing_type, idie_type_tbl.die_type, irevision_tbl.revision,
irelay_type_tbl.relay_type FROM imaster_tbl t1
LEFT JOIN idrawing_type_tbl ON imaster_tbl.drawing_type_id=idrawing_type_tbl.drawing_type_id
LEFT JOIN idie_type_tbl ON imaster_tbl.die_type_id = idie_type_tbl.die_type_id
LEFT JOIN irelay_type_tbl ON imaster_tbl.relay_type_id=irelay_type_tbl.relay_type_id 
LEFT JOIN irevision_tbl ON imaster_tbl.revision_id = irevision_tbl.revision_id 
WHERE revision = (SELECT MAX(revision) FROM imaster_tbl t2 WHERE t2.drawing_part_number = t1.drawing_part_number)

but this one works for me, without LEFT JOIN.

select * from table t1 where revision = (select max(revision) from table t2 where t2.filename = t1.filename)

thanks a lot.

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  • duanhan7001 2013-06-13 08:31
    关注

    The error states that the server cant find a specific field. It's a bit difficult to say if the field really exists, since you do not post your table definitions. But asuming it does exist you only have to replace imaster_tbl with t1 in you select part of the query. When you are writing "imaster_tbl t1" in the FROM part you are creating an alias of that table, and need to use the alias to reference fields in that table. Alias are usefull in e.g. when you want easier readability of the code, when creating temporary tables or when running the same table more than once, and need to identify how they connect.

    I've updated your SQL below

    SELECT
      t1.id,
      t1.die_name,
      t1.part_name,
      t1.drawing_number,
      t1.drawing_part_number,
      t1.sub_letter,
      t1.specs,
      t1.file_path,
      idrawing_type_tbl.drawing_type,
      idie_type_tbl.die_type,
      irevision_tbl.revision,
      irelay_type_tbl.relay_type
    FROM
      imaster_tbl t1
      LEFT JOIN idrawing_type_tbl ON
        master_tbl.drawing_type_id=idrawing_type_tbl.drawing_type_id
      LEFT JOIN idie_type_tbl ON
        imaster_tbl.die_type_id = idie_type_tbl.die_type_id
      LEFT JOIN irelay_type_tbl ON
        imaster_tbl.relay_type_id=irelay_type_tbl.relay_type_id 
      LEFT JOIN irevision_tbl ON
        imaster_tbl.revision_id = irevision_tbl.revision_id 
    WHERE
      revision = (
        SELECT
          MAX(revision)
        FROM
          imaster_tbl t2
        WHERE
          t2.drawing_part_number = t1.drawing_part_number
      )
    
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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