为什么我必须使用DISTINCT才能正常工作？

这里是我的问题：我有一个SQL查询，使查询表的4个调用从另一个表中的组合列表返回它们的值。我最终得到了这个工作，出于某种原因，当我在没有DISTINCT的情况下运行查询时，我得到大量数据，所以我猜测我要么丢失了某些东西，要么不正确地执行此操作。如果这不仅起作用，而且还按照第一个颜色名称的字母顺序返回列表，这将非常棒。我把我的SQL在这里，我希望我已经解释了这不够好：为什么我必须使用DISTINCT才能正常工作？

SELECT DISTINCT 
    colour1.ColourID AS colour1_ColourID, 
    colour1.ColourName AS colour1_ColourName, 
    colour1.ColourHex AS colour1_ColourHex, 
    colour1.ManufacturerColourID AS colour1_ManufacturerColourID, 
    colour2.ColourID AS colour2_ColourID, 
    colour2.ColourName AS colour2_ColourName, 
    colour2.ColourHex AS colour2_ColourHex, 
    colour2.QEColourID2 AS colour2_QEColourID2, 
    colour3.ColourID AS colour3_ColourID, 
    colour3.ColourName AS colour3_ColourName, 
    colour3.ColourHex AS colour3_ColourHex, 
    colour3.QEColourID3 AS colour3_QEColourID3, 
    colour4.ColourID AS colour4_ColourID, 
    colour4.ColourName AS colour4_ColourName, 
    colour4.ColourHex AS colour4_ColourHex, 
    colour4.QEColourID4 AS colour4_QEColourID4, 
    Combinations.ID, 
    Combinations.ManufacturerColourID AS Combinations_ManufacturerColourID, 
    Combinations.QEColourID2 AS Combinations_QEColourID2, 
    Combinations.QEColourID3 AS Combinations_QEColourID3, 
    Combinations.QEColourID4 AS Combinations_QEColourID4, 
    Combinations.ColourSupplierID, 
    ColourSuppliers.ColourSupplier 
FROM 
    ColourSuppliers INNER JOIN 
    (
     colour4 INNER JOIN 
     (
      colour3 INNER JOIN 
      (
       colour2 INNER JOIN 
       (
        colour1 INNER JOIN Combinations ON 
        colour1.ColourID=Combinations.ManufacturerColourID 
       ) ON colour2.ColourID=Combinations.QEColourID2 
      ) ON colour3.ColourID=Combinations.QEColourID3 
     ) ON colour4.ColourID=Combinations.QEColourID4 
    ) ON ColourSuppliers.ColourSupplierID=Combinations.ColourSupplierID 
WHERE Combinations.ColourSupplierID = ?

感谢斯蒂芬

来源

2010-06-28 stephmoreland

您可能想尝试重新格式化SQL查询以使其更易于阅读。 – Rich 2010-06-28 15:16:43

你能格式化那段代码吗？请不要将它全部放在一行中？这会让事情变得更容易。 – 2010-06-28 15:16:49

格式化它，但仍然是一个烂摊子 – 2010-06-28 15:21:06