mysql---(入门语句12--where详解)

#where详解

use mugua;//打开库

show tables;

select goods_id,goods_name from goods;

select *from goods;//取所有行所有列
select *from goods where goods_id >20;//取部分行所有列
select  goods_id,goods_name from goods where goods_id >20;//取部分行所有列

select goods_id,goods_name,shop_price,market_price from goods;

select goods_id,goods_name,shop_price,market_price from goods 
where shop_price>3000;//把商品价格大于3000的取出来

select goods_id,goods_name,shop_price,market_price from goods 
where market_price-shop_price>200;//把市场价格大于商场价格200的取出来

select goods_id,goods_name,shop_price from goods where shop_price <=3000;//取出本店价格少于等于3000的
select goods_id,goods_name,shop_price from goods where shop_price =3000;//取出本店价格等于3000的

#in

#查不属于第3号栏目的所有商品
1.select goods_id,cat_id,goods_name from goods where cat_id <>3;
2.select goods_id,cat_id,goods_name from goods where cat_id !=3;

#in(值1，值，值3.。。。值n)，等于值1-N任意一个，都行
#想查询第4个栏目或第5个栏目的商品
select goods_id cat_id,goods_name from goods where cat_id in (4,5);

#between

#between 值1 and 值2，表示在值1和值2之间
#取出商品价格在2000-3000之间的商品
select goods_id,goods_name,goods_price from goods where shop_price between 2000 and 3000;

#不用between and

#想买3000-5000之间的商品，但不用between and
select goods_id,goods_name,shop_price from goods where shop_price >=3000 and shop_price<=5000;

#or

#想买3000-5000之间的商品，或者500-1000的商品(同时满足)
select goods_id,goods_name,goods_price from goods where shop_price>=3000 and shop_price<=5000 
or shop_price>=500 and shop_price <=1000;

#not

#not 表示非
#not的用法：
#取出不属于第4,5栏目的商品
select goods_id,cat_id,goods_name from goods where cat_id !=4 and cat_id !=5;
#用not in来实现
select goods_id,cat_id,goods_name from goods where cat_id not in(4,5);

#模糊查询

#模糊查询
#案例：想查‘诺基亚开头的所有商品
like-->像
select goods_id,goods_name from goods where goods_name like '诺基亚';//取出来是空集

#统配符
%-->通佩任意字符
‘_’-->单个字符

select goods_id,goods_name from goods where goods_name like '诺基亚%';
#取‘诺基亚Nxxx’系列
select goods_id,goods_name from goods where goods_name like '诺基亚N_';