mysql 查询

简单的基本的sql语句

选择：select * from table1 where 范围
插入：insert into table1(field1,field2) values(value1,value2)
删除：delete from table1 where 范围
更新：update table1 set field1=value1 where 范围
查找：select * from table1 where field1 like ’%value1%’ ---like的语法很精妙，查资料!
排序：select * from table1 order by field1,field2 [desc]
总数：select count as totalcount from table1
求和：select sum(field1) as sumvalue from table1
平均：select avg(field1) as avgvalue from table1
最大：select max(field1) as maxvalue from table1
最小：select min(field1) as minvalue from table1

下列查询寻找雇员数超过 4 的部门的最高和最低薪水： 

SELECT WORKDEPT, MAX(SALARY) AS MAXIMUM, MIN(SALARY) AS MINIMUM 
FROM EMPLOYEE 
GROUP BY WORKDEPT 
HAVING COUNT(*) > 4 
ORDER BY WORKDEPT 

SELECT `uid`,`nickname`,MAX(`level`) as `level`,SUM(online_soon) AS online_soon,
        MAX(online_soon_all) AS online_soon_all,SUM(got_copper) AS got_copper,MAX(now_copper) AS now_copper,
        SUM(got_amber) AS got_amber,MAX(now_amber) AS now_amber,SUM(toy_times) AS toy_times,
        SUM(kill_monster_num) AS kill_monster_num,SUM(kill_moster_gold_num) AS kill_moster_gold_num 
        FROM top100_logs WHERE `statistic_date` BETWEEN 20160526 AND 20160526 GROUP BY `uid`,`nickname` HAVING COUNT(*) >0 ORDER BY `level` DESC LIMIT 0,100

1、说明：创建数据库
CREATE DATABASE database-name
2、说明：删除数据库
drop database dbname
3、说明：备份sql server
--- 创建 备份数据的 device
USE master
EXEC sp_addumpdevice 'disk', 'testBack', 'c:mssql7backupMyNwind_1.dat'
--- 开始 备份
BACKUP DATABASE pubs TO testBack
4、说明：创建新表
create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..)
根据已有的表创建新表：
A：create table tab_new like tab_old (使用旧表创建新表)
B：create table tab_new as select col1,col2… from tab_old definition only
5、说明：删除新表
drop table tabname
6、说明：增加一个列
Alter table tabname add column col type
注：列增加后将不能删除。DB2中列加上后数据类型也不能改变，唯一能改变的是增加varchar类型的长度。
7、说明：添加主键： Alter table tabname add primary key(col)
说明：删除主键： Alter table tabname drop primary key(col)
8、说明：创建索引：create [unique] index idxname on tabname(col….)
删除索引：drop index idxname
注：索引是不可更改的，想更改必须删除重新建。
9、说明：创建视图：create view viewname as select statement
删除视图：drop view viewname