Php 从多个列中选择“最小值”或“最大值”所在的id

我正在寻找一个快速的MySQL查询，它返回与所有价格类别（

a、b、c

和

d

）相比，具有最低（

min

）或最高（

max

）价格的产品id）

我有一个名为“巧克力库存”的产品表，有几个价格类别。从特定类别（

a

或

b

或

c

或

d

）收到最低（

min

）或最高（

max

）价格非常容易

价格类别为十进制（10,2）。下面是一个示例，它返回类别中的最高价格，但不返回id：

$t = 'chocolate_stock';
$arrIds = array(1, 3);

$strQuery = "SELECT id, 
             MAX(price_a) AS price_a, 
             MAX(price_b) AS price_b, 
             MAX(price_c) AS price_c, 
             MAX(price_d) AS price_d 
             FROM $t WHERE id IN(". implode(',', array_map('intval', $arrIds)) .")";

---

检索此信息的最快方法是什么？

您无法获取id，因为MAX返回一个值。但id不是这样。您可以使用单独的查询，如

SELECT id,MAX(price_a) FROM $t WHERE id IN (". implode(',', array_map('intval', $arrIds)).")";
SELECT id,MAX(price_b) FROM $t WHERE id IN (". implode(',', array_map('intval', $arrIds)).")";

---

etc

您没有获得id，因为MAX返回一个值。但id不是这样。您可以使用单独的查询，如

SELECT id,MAX(price_a) FROM $t WHERE id IN (". implode(',', array_map('intval', $arrIds)).")";
SELECT id,MAX(price_b) FROM $t WHERE id IN (". implode(',', array_map('intval', $arrIds)).")";

---

etc

如果您将希望输出的内容制成表格，可能会有所帮助，但我认为您缺少的是HAVING子句

首先，试试这个

select min(id), max(price_a) from $t having price_a = max(price_a)

然后试试看

select min(id), min(price_a) from $t having price_a = min(price_a)
union
select min(id), max(price_a) from $t having price_a = max(price_a)

---

如果您将希望输出的外观制成表格，可能会有所帮助，但我认为您缺少的部分是HAVING子句

首先，试试这个

select min(id), max(price_a) from $t having price_a = max(price_a)

然后试试看

select min(id), min(price_a) from $t having price_a = min(price_a)
union
select min(id), max(price_a) from $t having price_a = max(price_a)

---

此查询符合您的要求：

(select t.*
 from $t t
 where . . .
 order by price_a desc
 limit 1) union all
 (select t.*
 from $t t
 where . . .
 order by price_b desc
 limit 1) union all
(select t.*
 from $t t
 where . . .
 order by price_c desc
 limit 1) union all
(select t.*
 from $t t
 where . . .
 order by price_d desc
 limit 1)

如果您在

id

上有一个索引，那么它的性能应该相当好

这种方法需要对表进行四次遍历（尽管

id

上的索引应该会大大降低这一点）。以下方法只需通过表格一次：

select MAX(price_a),
       substring_index(group_concat(id order by price_a desc), ',', 1),
       max(price_b),
       substring_index(group_concat(id order by price_b desc), ',', 1),
       max(price_c),
       substring_index(group_concat(id order by price_c desc), ',', 1),
       max(price_d),
       substring_index(group_concat(id order by price_d desc), ',', 1)
from $t
where . . .

---

它使用

group_concat（）

和

substring_index（）

的技巧来获取每个列的最大id

此查询满足您的要求：

(select t.*
 from $t t
 where . . .
 order by price_a desc
 limit 1) union all
 (select t.*
 from $t t
 where . . .
 order by price_b desc
 limit 1) union all
(select t.*
 from $t t
 where . . .
 order by price_c desc
 limit 1) union all
(select t.*
 from $t t
 where . . .
 order by price_d desc
 limit 1)

如果您在

id

上有一个索引，那么它的性能应该相当好

这种方法需要对表进行四次遍历（尽管

id

上的索引应该会大大降低这一点）。以下方法只需通过表格一次：

select MAX(price_a),
       substring_index(group_concat(id order by price_a desc), ',', 1),
       max(price_b),
       substring_index(group_concat(id order by price_b desc), ',', 1),
       max(price_c),
       substring_index(group_concat(id order by price_c desc), ',', 1),
       max(price_d),
       substring_index(group_concat(id order by price_d desc), ',', 1)
from $t
where . . .

---

它使用

group_concat（）

和

substring_index（）

的技巧来获取每个列的最大id

您要做的第一件事是规范化数据，为了便于以后查询，我将创建以下视图：

CREATE VIEW NormalT
AS
    SELECT  ID, Name, 'Price_a' AS Type, Price_a AS Price
    FROM    T
    UNION ALL
    SELECT  ID, Name, 'Price_b' AS Type, Price_b AS Price
    FROM    T
    UNION ALL
    SELECT  ID, Name, 'Price_c' AS Type, Price_c AS Price
    FROM    T
    UNION ALL
    SELECT  ID, Name, 'Price_d' AS Type, Price_d AS Price
    FROM    T;

那么我不确定您想要的格式，如果您想要每个价格的最小值和最大值，您可以使用以下内容：

SELECT  mt.Type2,
        mt.Type,
        mt.Price,
        t.ID,
        t.Name
FROM    (   SELECT  Type, MIN(Price) AS Price, 'MIN' AS Type2
            FROM    NormalT
            GROUP BY Type
            UNION ALL
            SELECT  Type, MAX(Price) AS Price, 'MAX' AS Type2
            FROM    NormalT
            GROUP BY Type
        ) mt
        INNER JOIN NormalT T
            ON mt.Type = T.Type
            AND mt.Price = t.Price
ORDER BY mt.Type2, mt.Type, t.ID;

SELECT  mt.Type2,
        t.Type,
        mt.Price,
        t.ID,
        t.Name
FROM    (   SELECT  MIN(Price) AS Price, 'MIN' AS Type2
            FROM    NormalT
            UNION ALL
            SELECT  MAX(Price) AS Price, 'MAX' AS Type2
            FROM    NormalT
        ) mt
        INNER JOIN NormalT T
            ON mt.Price = t.Price;

将从示例数据中输出以下内容：

TYPE2   TYPE        PRICE   ID  NAME
MAX     Price_a     250     1   Chips Ahoy
MAX     Price_a     250     2   Chocolate Chunk
MAX     Price_b     530     1   Chips Ahoy
MAX     Price_c     720     1   Chips Ahoy
MAX     Price_d     850     3   Oreo
MIN     Price_a     103     3   Oreo
MIN     Price_b     44.52   3   Oreo
MIN     Price_c     32.92   2   Chocolate Chunk
MIN     Price_d     110     2   Chocolate Chunk

但是，如果它只是所有价格（a、b、c和d）的最小值和最大值，则可以使用：

SELECT  mt.Type2,
        mt.Type,
        mt.Price,
        t.ID,
        t.Name
FROM    (   SELECT  Type, MIN(Price) AS Price, 'MIN' AS Type2
            FROM    NormalT
            GROUP BY Type
            UNION ALL
            SELECT  Type, MAX(Price) AS Price, 'MAX' AS Type2
            FROM    NormalT
            GROUP BY Type
        ) mt
        INNER JOIN NormalT T
            ON mt.Type = T.Type
            AND mt.Price = t.Price
ORDER BY mt.Type2, mt.Type, t.ID;

SELECT  mt.Type2,
        t.Type,
        mt.Price,
        t.ID,
        t.Name
FROM    (   SELECT  MIN(Price) AS Price, 'MIN' AS Type2
            FROM    NormalT
            UNION ALL
            SELECT  MAX(Price) AS Price, 'MAX' AS Type2
            FROM    NormalT
        ) mt
        INNER JOIN NormalT T
            ON mt.Price = t.Price;

将输出以下内容：

TYPE2   TYPE    PRICE       ID  NAME
MIN     Price_c     32.92   2   Chocolate Chunk
MAX     Price_d     850     3   Oreo

---

您要做的第一件事是规范化数据，为便于以后查询，我将创建以下视图：

CREATE VIEW NormalT
AS
    SELECT  ID, Name, 'Price_a' AS Type, Price_a AS Price
    FROM    T
    UNION ALL
    SELECT  ID, Name, 'Price_b' AS Type, Price_b AS Price
    FROM    T
    UNION ALL
    SELECT  ID, Name, 'Price_c' AS Type, Price_c AS Price
    FROM    T
    UNION ALL
    SELECT  ID, Name, 'Price_d' AS Type, Price_d AS Price
    FROM    T;

那么我不确定您想要的格式，如果您想要每个价格的最小值和最大值，您可以使用以下内容：

SELECT  mt.Type2,
        mt.Type,
        mt.Price,
        t.ID,
        t.Name
FROM    (   SELECT  Type, MIN(Price) AS Price, 'MIN' AS Type2
            FROM    NormalT
            GROUP BY Type
            UNION ALL
            SELECT  Type, MAX(Price) AS Price, 'MAX' AS Type2
            FROM    NormalT
            GROUP BY Type
        ) mt
        INNER JOIN NormalT T
            ON mt.Type = T.Type
            AND mt.Price = t.Price
ORDER BY mt.Type2, mt.Type, t.ID;

SELECT  mt.Type2,
        t.Type,
        mt.Price,
        t.ID,
        t.Name
FROM    (   SELECT  MIN(Price) AS Price, 'MIN' AS Type2
            FROM    NormalT
            UNION ALL
            SELECT  MAX(Price) AS Price, 'MAX' AS Type2
            FROM    NormalT
        ) mt
        INNER JOIN NormalT T
            ON mt.Price = t.Price;

将从示例数据中输出以下内容：

TYPE2   TYPE        PRICE   ID  NAME
MAX     Price_a     250     1   Chips Ahoy
MAX     Price_a     250     2   Chocolate Chunk
MAX     Price_b     530     1   Chips Ahoy
MAX     Price_c     720     1   Chips Ahoy
MAX     Price_d     850     3   Oreo
MIN     Price_a     103     3   Oreo
MIN     Price_b     44.52   3   Oreo
MIN     Price_c     32.92   2   Chocolate Chunk
MIN     Price_d     110     2   Chocolate Chunk

但是，如果它只是所有价格（a、b、c和d）的最小值和最大值，则可以使用：

SELECT  mt.Type2,
        mt.Type,
        mt.Price,
        t.ID,
        t.Name
FROM    (   SELECT  Type, MIN(Price) AS Price, 'MIN' AS Type2
            FROM    NormalT
            GROUP BY Type
            UNION ALL
            SELECT  Type, MAX(Price) AS Price, 'MAX' AS Type2
            FROM    NormalT
            GROUP BY Type
        ) mt
        INNER JOIN NormalT T
            ON mt.Type = T.Type
            AND mt.Price = t.Price
ORDER BY mt.Type2, mt.Type, t.ID;

SELECT  mt.Type2,
        t.Type,
        mt.Price,
        t.ID,
        t.Name
FROM    (   SELECT  MIN(Price) AS Price, 'MIN' AS Type2
            FROM    NormalT
            UNION ALL
            SELECT  MAX(Price) AS Price, 'MAX' AS Type2
            FROM    NormalT
        ) mt
        INNER JOIN NormalT T
            ON mt.Price = t.Price;

将输出以下内容：

TYPE2   TYPE    PRICE       ID  NAME
MIN     Price_c     32.92   2   Chocolate Chunk
MAX     Price_d     850     3   Oreo

---

试试这个，它在模拟分析，因为MYSQL默认情况下没有这些分析：

SELECT id, 
             ( select MAX(price_a) from $t t2 where  t2.id = t1.id ) AS price_a, 
             ( select MAX(price_b) from $t t2 where  t2.id = t1.id ) AS price_b, 
             ( select MAX(price_c) from $t t2 where  t2.id = t1.id ) AS price_c, 
             ( select MAX(price_d) from $t t2 where  t2.id = t1.id ) AS price_d 
             FROM $t t1 WHERE id IN(". implode(',', array_map('intval', $arrIds)) .")

---

来源：

试试这个，它是在模拟分析，因为MYSQL默认没有这些分析：

SELECT id, 
             ( select MAX(price_a) from $t t2 where  t2.id = t1.id ) AS price_a, 
             ( select MAX(price_b) from $t t2 where  t2.id = t1.id ) AS price_b, 
             ( select MAX(price_c) from $t t2 where  t2.id = t1.id ) AS price_c, 
             ( select MAX(price_d) from $t t2 where  t2.id = t1.id ) AS price_d 
             FROM $t t1 WHERE id IN(". implode(',', array_map('intval', $arrIds)) .")

---

来源：

为了安全起见：您希望有两条结果记录；给定您的示例数据和一个包含所有三项的查询（即不包含WHERE子句）：min=（id:2，price\u c:32.92）和max=（id:3，price\u d:850）？是的，我知道。我可以在以后限制它们或对结果重新排序。您希望的输出是什么？具体来说，如果最高价格为250，并且有两种产品的最高价格为250，您对最高价格的期望是什么？如果速度很重要，请规范化您的数据。哦，价格类别是十进制的（10,2）？提醒我不要吃你的奥利奥！为了安全起见：您希望有两个结果记录；给定您的示例数据和一个包含所有三项的查询（即不包含WHERE子句）：min=（id:2，price\u c:32.92）和max=（id:3，price\u d:850）？是的，我知道。我可以在以后限制它们或对结果重新排序。您希望的输出是什么？具体来说，如果最高价格为250，并且有两种产品的最高价格为250，您对最高价格的期望是什么？如果速度很重要，请规范化您的数据。哦，价格类别是十进制的（10,2）？提醒我不要吃你的奥利奥！非常感谢。这不可能在一个查询中实现吗？不，不可能。这是因为MAX、MIN、AVG和all都返回一条记录。不是多重的。出于您的原因，您将需要多个ID，每个区域的最高和最低价格。那是不可能的，谢谢。这不可能在一个查询中实现吗？不，不可能。这是因为MAX、MIN、AVG和all都返回一条记录。不是多重的。出于您的原因，您将需要多个ID，每个区域的最高和最低价格。这是不可能的。