1.插入数据insert into表名(列名1,列名2,列名..) values(值1,值2,值...);
insert into product(name, price, pic_path) values('nike',500,'uploads/3245.jpg');
2.更新数据
update 表名set列名1=值1,列名2=值2[where条件];
update product set name='lining', price=50where id=2;
3.删除数据
deletefrom表名[where条件];
deletefrom product where id=2;
4.查询所有数据
select*from表名;select*from product;
5.查询部份列
select列名1,列名2,列名n from表名;
select name, price from product;
6.条件查询
# 比较 =, <, >, <=, >=, !=
select*from表名where列名=值;
select*from product where id=2;
# and 与
select*from表名where条件1and条件2and条件n;
select*from product where name='nike'and price=50;
# or 或
select*from表名where条件1or条件2or条件n;
select*from product where name='nike'or price>50;
# not 非
select*from表名wherenot条件1;
select*from product wherenot name='nike';
#in 枚举
select*from表名where列名in(值1,值2,值n);
select*from product where id in(2,3,4,10);
select*from product where id notin(2,3,4,10);
#like 模糊查询
select*from表名where列名 like '%值%';
select*from product where name like '%li%';
#between...and... 范围查询
select*from表名where列名 between 值and值;
select*from order where created between '2010-01-01'and'2011-01-01';
7.查询排序
select*from表名 order by列名排序方式;
#排序方式: asc(升序，默认)，desc(降序)
select*from product order by created desc;
8.限制查询结果数量
select*from表名 limit 开始记录数,结果数量;select*from product limit 5;
select*from product limit 2,5;
9.聚合函数
# count 总记录数
select count(列名)from student;
select count(id)from student;
# sum 总共
select sum(列名)from student;
select sum(age)from student;
# avg 平均值
select avg(列名)from student;
select avg(age)as avg_age from student;
# max 最大值
select max(列名)from student;
select max(age)from student;
# min 最小值
select min(列名)from student;
select min(age)from student;
10.子查询
select name from student where age<(select avg(age)from student );
select*from product where id in(select id from order );
11.连接查询
select s.username as stu_name, t.name as te_name from student s, teacher t where s.teacher_id=t.id;
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