MySQL查询语句

查询属性：

SELECT	读取一条或者多条记录
FROM	设定查询来源
WHERE	设定查询条件
GROUP BY	设定查询分组（GROUP BY会把相同的值分为一组）
HAVING	设定过滤内容
ORDER BY	设定查询排序
LIMIT	设定返回的记录数 例如：0,1 下标为0的开始，到下标为1的结束

查询顺序

select ' ' from '' where '' group by '' having '' order by '' limit ''

示例：

1. FROM

查询整个order表

select * FROM `order`

查询 order 表下面的order_numbe

select `order_number` FROM `order`

2. WHERE

查询order 表下面某一条order_number

select `order_number` FROM `order` WHERE order_number='A809190953095031'

查询order 表下面多条order_numbe

select `order_number` FROM `order` WHERE order_number IN ('A809190953095031','A809191884980807')

3. GROUP BY

count	统计数量
SUM	求和
MAX	最大值
MIN	最小值
AVG	平均值
first	第一条记录
last	最后一条记录

a. count - 统计数量

查询order下相同订单号（order_number）的分组及每组数量

select order_number, count(*) FROM `order` GROUP BY order_number

b. SUM - 求和

查询order下相同订单号（order_number）的分组及每组价格（price）总和

select order_number, SUM(price) FROM `order` GROUP BY order_number

查询order下相同订单号（order_number）的分组及每组价格（price）和 商品价（goods_sum_price）总和

select order_number, SUM(price) + SUM(goods_sum_price) FROM `order` GROUP BY order_number

 c. MAX - 最大值

查询order下相同订单号（order_number）的分组及每组最大价格

select order_number, MAX(price) FROM `order` GROUP BY order_number

 d. MIN - 最小值

查询order下相同订单号（order_number）的分组及每组最小价格

select order_number, MIN(price) FROM `order` GROUP BY order_number

e. AVG - 平均值

查询order下相同订单号（order_number）的分组及每组价格的平均值

select order_number, AVG(price) FROM `order` GROUP BY order_number