数据库的增删改查

select * from Fruit
添加
insert into Fruit values('K008','柿子',3.0,'山西',90,'')
insert into Fruit values('K009','火龙果',5.0,'福建',110,'')
insert into Fruit(Ids,Name,Price,Source,Numbers) values('K010','苹果',3.0,'高青',90)

查询
select distinct Numbers from Fruit               --查指定行 （去重显示）
select * from News                               --模糊查询
select * from News where title like '%贷款%'   --查包含
select * from News where title like '%现代_'     --_后面只能有一个字符

排序
select * from Fruit order by Numbers asc         --不加asc默认升序排列，desc代表降序
select * from Fruit order by Numbers ,Price asc  -- 先按前面的排一遍，在用后面的排一遍

select COUNT (1) from  Fruit    --返回表里有多少条数据    括号内*代表全部，写1节省运算量
select AVG (Numbers) from Fruit                  --所选列平均值
select SUM (Numbers) from Fruit                  --所选列总值
select MAX (Numbers) from Fruit                  --所选列最大值
select MIN (Numbers) from Fruit                  --所选列最小值
select*,(Price*0.8) as'折后价格'from Fruit       --添加一列，八折价格，as可以省略

分组查询
select COUNT (Numbers) from Fruit group by  Numbers  -- 求该组成员个数
select Numbers,COUNT(*) from Fruit group by  Numbers   having  COUNT(*)>1 -- 筛选大于1的
修改
update Fruit set Source='栖霞' where Ids='K001'
删除
delete from Fruit where Ids='K010'
 
delete from Fruit where Source='高青'            -- 删除一整行
如果误删除，可恢复
事务：出现了错误，可以进行回滚

加事务：begin tran

回滚：rollback
begin tran
delete from Fruit where Ids='K010'
rollback