存储过程和事务
存储过程和函数很像,但和函数的区别就是函数有返回值,存储过程没有返回值,存储过程是很多的sql语句组成
事务具有原子性,里面是很多的sql语句,要不一次全部成功,要不执行失败开始回滚
-- alter table test2
add column NAME CHAR -- 增加一列
-- create table test11 like test -- 创建一个像旧表的新表
-- alter table test add PRIMARY KEY(Id) -- 添加主键
-- alter table test drop primary key(Id) -- 删除主键
-- select * from offices where city='london' -- where 选择范围
-- insert into test(Id,age) values(1,24) -- 插入一条数据
-- update test set age=21 where Id=2 -- 更新指定范围的数据
-- select orderNumber from orders order by orderDate -- 排序
-- select sum(orderNumber) as sumvalues from orders -- 求和
-- select count(orderNumber) as tatalcount from orders -- 总数
-- select avg(orderNumber) as avgvalue from orders -- 求平均值
-- select max(orderNumber) as maxvalue from orders -- 求最大值
-- select min(orderNumber) as minvalue from orders -- 求最小值
-- explain select orders.customerNumber
,offices.city
FROM orders right join offices on orders.customerNumber
= offices.city
-- select DISTINCT orderNumber from orders -- 去重
-- select * from orders where orderNumber between 10352 and 10403 -- 筛选指定范围的数据
-- select * from orders where orderNumber not between 10352 and 10403 -- 筛选不在这个范围内的数据
-- select * from offices where city
in ('London','Boston') -- 筛选在某个范围的数据
-- select * from offices where city
not in ('London','Boston') -- 筛选不在某个范围的数据
-- select orderNumber,date_format(now(),'%Y-%m-%d') as Date from orders -- format 格式化
-- select orderNumber from orders union select employeeNumber
from employees -- 连接2个表的字段,字段类型要相同