SQL的基本操作
1. insert into语句
insert into （列名1，列名2….）values（1,’技术部’）
insert into xinzhan values (2,’市场部’ )
2. select 语句
select 列 from表 where 条件 order by 排序
select*from表
3. update 语句
update表set列内容 where条件
update xinzhan set userpassword = ‘123.com’
update xinzhan set usermoney=usermoney +200 where username=’某某’
4. delete 语句
delete from表where条件
delete from xinzhan where username=’路人甲’
delete from xinzhan where usermoney<1000
SQL的高级查询
1. 查询电话号码为12101150818的电话费
1. 统计出所有电话应该交的电话费（市话话费加上长途话费）
1. 4.将联合查找出的用户名和话费记录到新表中
2. SELECT '电话' + cast(call.phonenumber as varchar(11)) + '费用' + cast((SUM(DATEDIFF(MI,call.starttime,call.endtime))
3. + SUM(DATEDIFF(MI,[call-history].starttime,[call-history].endtime))) * 0.7 as varchar(20))
4.
5. FROM call INNER JOIN
6. [call-history] ON call.phonenumber = [call-history].phonenumber
7.
8.
9. where call.calltype=1 and [call-history].calltype=1
10. group by call.phonenumber,[call-history].phonenumber
