MySQL每个类别最新的⼀条记录⽂章⽬录
问题描述
商品表 Product
SQL语句
-- 创建表
video gamesCREATE TABLE Product
(
linker
product_id CHAR(4)NOT NULL,七夕英语
product_name VARCHAR(100)NOT NULL,
product_type VARCHAR(32)NOT NULL,
sale_price INTEGER,
purcha_price INTEGER,
regist_date DATE,
PRIMARY KEY(product_id)
);
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-- 插⼊数据
BEGIN TRANSACTION;
INSERT INTO Product VALUES('0001','T恤衫','⾐服',1000,500,'2009-09-20');
INSERT INTO Product VALUES('0002','打孔器','办公⽤品',500,320,'2009-9-11');
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INSERT INTO Product VALUES('0003','运动T恤','⾐服',4000,2800,NULL);
INSERT INTO Product VALUES('0004','菜⼑','厨房⽤具',3000,2800,'2009-9-20');
INSERT INTO Product VALUES('0005','⾼压锅','厨房⽤具',6800,5000,'2009-1-15');
INSERT INTO Product VALUES('0006','叉⼦','厨房⽤具',500,NULL,'2009-9-20');
INSERT INTO Product VALUES('0007','擦菜板','厨房⽤具',880,790,'2008-4-28');
INSERT INTO Product VALUES('0008','圆珠笔','办公⽤品',100,NULL,'2009-11-11');
COMMIT;vlcc
解决⽅案
1. 原表
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SELECT*FROM Product;
金妍儿冬奥会2. GROUP BY 类别，取出 主键 和 max(时间)
redflagSELECT*,max(regist_date)FROM Product GROUP BY product_type;
3. INNER JOIN，ON 主键，某些情况还得要 ON max(时间)
SELECT*FROM Product AS t1
INNER JOIN(
SELECT product_id,max(regist_date)AS regist_date FROM Product GROUP BY product_type )AS t2
sinocomON t1.product_id=t2.product_id
# ist_ist_date
参考⽂献
1.
