mysql分组取前几条记录

测试sql语句

CREATE TABLE `mygoods` (  
  `goods_id` int(11) unsigned NOT NULL AUTO_INCREMENT,  
  `cat_id` int(11) NOT NULL DEFAULT '0',  
  `price` tinyint(3) NOT NULL DEFAULT '0',  
  `status` tinyint(3) DEFAULT '1',  
  PRIMARY KEY (`goods_id`),  
  KEY `icatid` (`cat_id`)  
) ENGINE=InnoDB  DEFAULT CHARSET=utf8;

INSERT INTO `mygoods` VALUES (1, 101, 90, 0);  
INSERT INTO `mygoods` VALUES (2, 101, 99, 1);  
INSERT INTO `mygoods` VALUES (3, 102, 98, 0);  
INSERT INTO `mygoods` VALUES (4, 103, 96, 0);  
INSERT INTO `mygoods` VALUES (5, 102, 95, 0);  
INSERT INTO `mygoods` VALUES (6, 102, 94, 1);  
INSERT INTO `mygoods` VALUES (7, 102, 93, 1);  
INSERT INTO `mygoods` VALUES (8, 103, 99, 1);  
INSERT INTO `mygoods` VALUES (9, 103, 98, 1);  
INSERT INTO `mygoods` VALUES (10, 103, 97, 1);  
INSERT INTO `mygoods` VALUES (11, 104, 96, 1);  
INSERT INTO `mygoods` VALUES (12, 104, 95, 1);  
INSERT INTO `mygoods` VALUES (13, 104, 94, 1);  
INSERT INTO `mygoods` VALUES (15, 101, 92, 1);  
INSERT INTO `mygoods` VALUES (16, 101, 93, 1);  
INSERT INTO `mygoods` VALUES (17, 101, 94, 0);  
INSERT INTO `mygoods` VALUES (18, 102, 99, 1);  
INSERT INTO `mygoods` VALUES (19, 105, 85, 1);  
INSERT INTO `mygoods` VALUES (20, 105, 89, 0);  
INSERT INTO `mygoods` VALUES (21, 105, 99, 1); 

表mygoods为商品表,cat_id为分类id,goods_id为商品id,status为商品当前的状态位(1:有效,0:无效)。

需求

1、每个分类下,找出两个价格最高的商品。

SELECT
    a.* 
FROM
    mygoods a 
WHERE
    (
    SELECT
        count( * ) 
    FROM
        mygoods b 
    WHERE
        a.cat_id = b.cat_id 
        AND a.price > b.price 
    ) < 2 
ORDER BY
    a.cat_id,
    a.price DESC;

2、每个分类找出价格最高的【有效的】两个商品

第一种写法

SELECT
    a.* 
FROM
    mygoods a 
WHERE
    (
    SELECT
        count( * ) 
    FROM
        mygoods b 
    WHERE
        a.cat_id = b.cat_id 
        AND a.price > b.price 
        AND b.STATUS = 1 
    ) < 2 
    AND a.STATUS = 1 
ORDER BY
    a.cat_id,
    a.price DESC;

第二种写法

SELECT
    a.* 
FROM
    mygoods a
    LEFT JOIN mygoods b ON a.cat_id = b.cat_id 
    AND a.price < b.price 
    AND b.STATUS = 1 
WHERE
    a.STATUS = 1 
GROUP BY
    a.goods_id,
    a.cat_id,
    a.price 
HAVING
    count( b.goods_id ) < 2 
ORDER BY
    a.cat_id,
暂无评论

发送评论 编辑评论


|´・ω・)ノ
ヾ(≧∇≦*)ゝ
(☆ω☆)
(╯‵□′)╯︵┴─┴
 ̄﹃ ̄
(/ω\)
∠( ᐛ 」∠)_
(๑•̀ㅁ•́ฅ)
→_→
୧(๑•̀⌄•́๑)૭
٩(ˊᗜˋ*)و
(ノ°ο°)ノ
(´இ皿இ`)
⌇●﹏●⌇
(ฅ´ω`ฅ)
(╯°A°)╯︵○○○
φ( ̄∇ ̄o)
ヾ(´・ ・`。)ノ"
( ง ᵒ̌皿ᵒ̌)ง⁼³₌₃
(ó﹏ò。)
Σ(っ °Д °;)っ
( ,,´・ω・)ノ"(´っω・`。)
╮(╯▽╰)╭
o(*////▽////*)q
>﹏<
( ๑´•ω•) "(ㆆᴗㆆ)
😂
😀
😅
😊
🙂
🙃
😌
😍
😘
😜
😝
😏
😒
🙄
😳
😡
😔
😫
😱
😭
💩
👻
🙌
🖕
👍
👫
👬
👭
🌚
🌝
🙈
💊
😶
🙏
🍦
🍉
😣
Source: github.com/k4yt3x/flowerhd
颜文字
Emoji
小恐龙
花!
上一篇
下一篇