获得每个商店中销售量最高的产品 - 不断收到错误的产品但数量合适

Question

对于下表，我想获得一个表格，显示每个商店中销售量最大的产品 同一产品可以在超过1家商店中销售最多。

这是我试过的查询：

SELECT StoreID, ProductID, MAX(Quantity), TotalPrice FROM MyTable GROUP BY StoreID LIMIT 0, 99999;

我得到的答案是：

|StoreID|ProductID|MAX(Quantity)|TotalPrice
'1', '1', '566', '288.0000'
'2', '1', '782', '648.0000'
'3', '1', '473', '172.8000'

问题： 我检查过，最大数量是正确的 但出于某种原因，它显示每个产品的ID为'1'，即使它不是任何商店中销售最多的产品。

对于此表（称为“MyTable”）：

|StoreID|TotalPrice|ProductID|Quantity
'1', '288.0000', '1', '167'
'1', '760.0000', '2', '417'
'1', '400.0000', '3', '70'
'1', '352.0000', '4', '218'
'1', '1105.0000', '5', '117'
'1', '600.0000', '6', '156'
'1', '300.0000', '7', '193'
'1', '960.0000', '8', '84'
'1', '1552.0000', '9', '36'
'1', '558.0000', '10', '115'
'1', '201.6000', '11', '218'
'1', '152.0000', '12', '8'
'1', '9.6000', '13', '187'
'1', '167.4000', '14', '47'
'1', '62.0000', '15', '42'
'1', '417.0000', '16', '451'
'1', '936.0000', '17', '345'
'1', '450.0000', '18', '112'
'1', '7.3000', '19', '68'
'1', '1701.0000', '20', '66'
'1', '80.0000', '21', '337'
'1', '100.8000', '22', '58'
'1', '151.2000', '23', '275'
'1', '43.2000', '24', '431'
'1', '44.8000', '25', '171'
'1', '1245.0000', '26', '297'
'1', '526.5000', '27', '185'
'1', '1528.8000', '28', '127'
'1', '1485.0000', '29', '61'
'1', '124.2000', '30', '158'
'1', '600.0000', '31', '566'
'1', '153.6000', '32', '91'
'1', '120.0000', '33', '294'
'1', '112.0000', '34', '62'
'1', '57.6000', '35', '249'
'1', '456.0000', '36', '200'
'1', '208.0000', '37', '18'
'1', '4216.0000', '38', '86'
'1', '57.6000', '39', '192'
'1', '735.0000', '40', '431'
'1', '123.2000', '41', '220'
'1', '22.4000', '42', '183'
'1', '920.0000', '43', '141'
'1', '325.5000', '44', '281'
'1', '114.0000', '45', '360'
'1', '288.0000', '46', '249'
'1', '418.0000', '47', '156'
'1', '191.2500', '48', '45'
'1', '240.0000', '49', '45'
'1', '406.2500', '50', '25'
'1', '1696.0000', '51', '271'
'1', '112.0000', '52', '146'
'1', '1048.0000', '53', '202'
'1', '59.0000', '54', '180'
'1', '384.0000', '55', '147'
'1', '2128.0000', '56', '428'
'1', '234.0000', '57', '146'
'1', '318.0000', '58', '201'
'1', '3080.0000', '59', '504'
'1', '544.0000', '60', '433'
'1', '364.8000', '61', '221'
'1', '591.0000', '62', '247'
'1', '2808.0000', '63', '187'
'1', '1330.0000', '64', '194'
'1', '336.0000', '65', '250'
'1', '816.0000', '66', '110'
'1', '56.0000', '67', '105'
'1', '30.0000', '68', '245'
'1', '432.0000', '69', '305'
'1', '252.0000', '70', '254'
'1', '344.0000', '71', '326'
'1', '556.0000', '72', '400'
'1', '240.0000', '73', '143'
'1', '400.0000', '74', '70'
'1', '186.0000', '75', '490'
'1', '216.0000', '76', '348'
'1', '104.0000', '77', '255'
'2', '648.0000', '1', '317'
'2', '608.0000', '2', '453'
'2', '160.0000', '3', '128'
'2', '422.4000', '4', '109'
'2', '85.4000', '5', '124'
'2', '150.0000', '6', '77'
'2', '240.0000', '7', '332'
'2', '2240.0000', '8', '222'
'2', '4850.0000', '9', '53'
'2', '396.8000', '10', '435'
'2', '403.2000', '11', '293'
'2', '570.0000', '12', '107'
'2', '96.0000', '13', '477'
'2', '279.0000', '14', '224'
'2', '155.0000', '15', '60'
'2', '139.0000', '16', '294'
'2', '468.0000', '17', '416'
'2', '2000.0000', '18', '218'
'2', '109.5000', '19', '422'
'2', '2592.0000', '20', '219'
'2', '160.0000', '21', '286'
'2', '201.6000', '22', '204'
'2', '180.0000', '23', '187'
'2', '54.0000', '24', '363'
'2', '134.4000', '25', '120'
'2', '249.0000', '26', '164'
'2', '1755.0000', '27', '80'
'2', '1019.2000', '28', '281'
'2', '1980.0000', '29', '458'
'2', '165.6000', '30', '175'
'2', '200.0000', '31', '533'
'2', '1024.0000', '32', '176'
'2', '50.0000', '33', '233'
'2', '156.8000', '34', '158'
'2', '288.0000', '35', '348'
'2', '608.0000', '36', '359'
'2', '468.0000', '37', '18'
'2', '4216.0000', '38', '292'
'2', '604.8000', '39', '317'
'2', '588.0000', '40', '518'
'2', '77.0000', '41', '301'
'2', '112.0000', '42', '223'
'2', '552.0000', '43', '298'
'2', '248.0000', '44', '136'
'2', '380.0000', '45', '40'
'2', '48.0000', '46', '230'
'2', '121.6000', '47', '197'
'2', '153.0000', '48', '15'
'2', '640.0000', '49', '344'
'2', '195.0000', '50', '101'
'2', '1484.0000', '51', '328'
'2', '44.8000', '52', '198'
'2', '393.0000', '53', '320'
'2', '59.0000', '54', '295'
'2', '403.2000', '55', '283'
'2', '121.6000', '56', '486'
'2', '249.6000', '57', '202'
'2', '318.0000', '58', '102'
'2', '660.0000', '59', '630'
'2', '1088.0000', '60', '782'
'2', '2052.0000', '61', '177'
'2', '591.0000', '62', '399'
'2', '280.8000', '63', '223'
'2', '931.0000', '64', '397'
'2', '252.0000', '65', '229'
'2', '408.0000', '66', '95'
'2', '210.0000', '67', '55'
'2', '200.0000', '68', '298'
'2', '518.4000', '69', '232'
'2', '240.0000', '70', '299'
'2', '34.4000', '71', '258'
'2', '667.2000', '72', '200'
'2', '300.0000', '73', '85'
'2', '168.0000', '74', '92'
'2', '37.2000', '75', '542'
'2', '86.4000', '76', '367'
'2', '124.8000', '77', '236'
'3', '172.8000', '1', '344'
'3', '304.0000', '2', '187'
'3', '240.0000', '3', '130'
'3', '1100.0000', '4', '126'
'3', '204.0000', '5', '57'
'3', '120.0000', '6', '68'
'3', '360.0000', '7', '238'
'3', '400.0000', '8', '66'
'3', '582.0000', '9', '6'
'3', '595.2000', '10', '192'
'3', '168.0000', '11', '195'
'3', '364.8000', '12', '229'
'3', '48.0000', '13', '227'
'3', '167.4000', '14', '133'
'3', '248.0000', '15', '20'
'3', '486.5000', '16', '413'
'3', '249.6000', '17', '217'
'3', '600.0000', '18', '209'
'3', '131.4000', '19', '233'
'3', '1814.4000', '20', '28'
'3', '80.0000', '21', '393'
'3', '840.0000', '22', '86'
'3', '288.0000', '23', '118'
'3', '100.8000', '24', '331'
'3', '112.0000', '25', '27'
'3', '597.6000', '26', '292'
'3', '877.5000', '27', '100'
'3', '728.0000', '28', '232'
'3', '990.0000', '29', '227'
'3', '1242.0000', '30', '279'
'3', '150.0000', '31', '298'
'3', '320.0000', '32', '30'
'3', '40.0000', '33', '228'
'3', '224.0000', '34', '286'
'3', '1440.0000', '35', '286'
'3', '380.0000', '36', '246'
'3', '20.8000', '37', '89'
'3', '10540.0000', '38', '245'
'3', '86.4000', '39', '284'
'3', '882.0000', '40', '154'
'3', '192.5000', '41', '460'
'3', '98.0000', '42', '291'
'3', '1472.0000', '43', '141'
'3', '620.0000', '44', '184'
'3', '228.0000', '45', '108'
'3', '144.0000', '46', '69'
'3', '114.0000', '47', '132'
'3', '714.0000', '48', '78'
'3', '560.0000', '49', '131'
'3', '195.0000', '50', '109'
'3', '127.2000', '51', '287'
'3', '112.0000', '52', '156'
'3', '262.0000', '53', '200'
'3', '29.5000', '54', '280'
'3', '2304.0000', '55', '473'
'3', '60.8000', '56', '349'
'3', '312.0000', '57', '86'
'3', '848.0000', '58', '231'
'3', '1320.0000', '59', '362'
'3', '952.0000', '60', '362'
'3', '712.5000', '61', '205'
'3', '472.8000', '62', '437'
'3', '175.5000', '63', '35'
'3', '239.4000', '64', '149'
'3', '672.0000', '65', '266'
'3', '136.0000', '66', '34'
'3', '336.0000', '67', '24'
'3', '100.0000', '68', '256'
'3', '28.8000', '69', '177'
'3', '60.0000', '70', '264'
'3', '516.0000', '71', '473'
'3', '174.0000', '72', '206'
'3', '525.0000', '73', '65'
'3', '288.0000', '74', '135'
'3', '37.2000', '75', '123'
'3', '475.2000', '76', '266'
'3', '156.0000', '77', '300'

Answer 1

尝试以下内容：

SELECT * 
FROM MyTable WHERE (storeID,Quantity) IN 
( SELECT storeID, MAX(Quantity)
  FROM MyTable 
  GROUP BY storeID
)

Answer 2

你写的查询含糊不清。 ProductID 不具有最大数量的产品。想想这个问题：

SELECT StoreID, ProductID, MAX(Quantity), MIN(Quantity), TotalPrice 
FROM MyTable 
GROUP BY StoreID LIMIT 0, 99999;

您希望此查询返回哪个ProductID？具有最大数量的产品或具有最小数量的产品？

或者这个：

SELECT StoreID, ProductID, AVG(Quantity), TotalPrice 
FROM MyTable 
GROUP BY StoreID LIMIT 0, 99999;

也许没有产品的数量恰好是平均数量。

这种类型的SQL查询在技术上是非法的，并且在MySQL以外的大多数数据库中都是错误的。 MySQL允许它，并且相信你何时会写出这样一个模棱两可的查询。

提示：选择列表的每一列都必须是：

• 在aggregate function
内
• 以GROUP BY子句命名。

任何其他列都不会返回可靠的值。

您要求的查询被称为greatest-n-per-group问题。这个问题在Stack Overflow上经常出现，并且已经多次回答。这里有几个我过去的答案得到了很多赞成：

• Retrieving the last record in each group
• Fetch the row which has the Max value for a column

Answer 3

匹配，因为您按StoreID分组。 MAX是GROUP BY函数，因此它返回每个StoreID的MAX（Quantity）。

对于ProductID和TotalPrice，查询只返回每个商店第一行的值，因为没有什么可以告诉它读取Quantity = MAX（Quantity）

行的值

另一方面，TheUknown的查询首先找到每个商店的MAX（数量），然后执行第二个查询以返回Quantity = MAX（Quantity）

行的所有字段