无法在 4 table 查询中显示所有结果

Question

我有零件 table 和价格 table 部件 table 引用自身与保修部件号相关。

我想运行查询以显示所有部件，如果他们有保修，请提供保修的部件号和价格。

select `P`.`partNumber` AS `partNumber`,`P`.`Description` AS `Description`,`PP`.`Price` AS `Price`,`P`.`WarrantyPartNumber` AS `WarrantyPartNumber`,`W`.`Description` AS `WDescription`
from ((`tblPart` `P` left outer join `tblPart` `W` on `P`.`WarrantyPartNumber` = `W`.`partNumber`)  inner join `tblPartPrice` `PP` on `P`.`partNumber` = `PP`.`partNumber`) 
where PP.tierID = 0

以上给出了正确的输出但没有价格。一旦我添加保修价目表参考，我只会看到显示保修的零件。

select `P`.`partNumber` AS `partNumber`,`P`.`Description` AS `Description`,`PP`.`Price` AS `Price`,`P`.`WarrantyPartNumber` AS `WarrantyPartNumber`,`W`.`Description` AS `WDescription`, `wPP`.`Price` AS `wPrice`  
from ((`tblPart` `P` left outer join `tblPart` `W` on `P`.`WarrantyPartNumber` = `W`.`partNumber`)  inner join `tblPartPrice` `PP` on `P`.`partNumber` = `PP`.`partNumber`) right outer join `tblPartPrice` `wPP` on `W`.`partNumber` = `wPP`.`partNumber`
where PP.tierID = 0 AND wPP.tierID = 0

预期结果

All parts with or without warranty showing cost of any warranty elements if present.

Answer 1

这是您的查询，已修改为至少可读：

select p.partNumber, p.Description, pp.Price, 
       pp.WarrantyPartNumber,
       w.Description AS WDescription, wPP.Price AS wPrice
from tblPart p left outer join
     tblPart w
     on p.WarrantyPartNumber = w.partNumber inner join
     tblPartPrice pp
     on p.partNumber = pp.partNumber right outer join
     tblPartPrice wPP
     on w.partNumber = wPP.partNumber
where PP.tierID = 0 AND wPP.tierID = 0;

用 where 子句混合左右连接非常复杂。您的查询似乎可以使用更简单的方法。

如果我没理解错的话，保修部件的等级必须相同。因此，这个条件应该在 on 子句中：

select p.partNumber, p.Description, pp.Price, 
       pp.WarrantyPartNumber,
       w.Description AS WDescription, wPP.Price AS wPrice
from tblPart p join
     tblPartPrice pp
     on p.partNumber = pp.partNumber left outer join
     tblPart w
     on p.WarrantyPartNumber = w.partNumber left join
     tblPartPrice wpp
     on w.partNumber = wpp.partNumber and
        wpp.tierID = pp.TierId
where pp.tierID = 0;

注意 joins:

p inner join pp 因为这些应该匹配。您期望每个零件的价格。
left join w因为可能没有保修部分
left join wpp因为之前的left join可能没有找到匹配的行。

无法在 4 table 查询中显示所有结果

Cant Get All results to show on a 4 table query

mysql

sql

alias