创建表：
CREATE TABLE `biao` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT COMMENT '测试表', `createtime` datetime DEFAULT NULL COMMENT '时间', `title` varchar(10) CHARACTER SET latin1 DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8;
删除表：
DROP TABLE IF EXISTS `biao`;
DROP TABLE IF EXISTS t1,t2;
显示表结构,简写desc：describe biao
显示表结构语句：show create table biao
修改表名：alter table old rename new
显示表结构：show tables
修改字段类型：alter table biao modify id int(5)
修改表字段,新旧字段一样和modify就一样功能：
ALTER TABLE test ADD qqq VARCHAR(10) DEFAULT '1' NOT NULL
ALTER TABLE test CHANGE test test1 CHAR(32) NOT NULL DEFAULT '123';
删除字段：ALTER TABLE ims_mm DROP ttt
定义主键 primary key
非空 not null
唯一性 unique
默认值 default
自动 auto_increment
函数：随机数 rand()
连接字符串 concat('中国','打日本')
转换小写 lcase('ABC') lower
转换大写 upper ucase
去除空格 trim(str)
获取日期
curdate()+0 返回20160916 curdate() 2016-09-16 时间
curtime() 日期时间 now()
时间戳
UNIX_TIMESTAMP(), UNIX_TIMESTAMP(now()) 日期转换时间戳 FROM_UNIXTIME( 1539659520) 时间戳转换成日期时间 月份
month('2016-04-28') 季度,1,2,3,4
QUARTER('2016-04-28') 星期
DAYOFWEEK('2016-04-28') 1是星期日 weekday 0是星期1 天数
DAYOFYEAR('2016-04-28') 1-366 年 year
分钟 minute
小时 hour
秒 second
版本version
聚合函数
avg(col) 平均值
count(*) 记录数
min(col) max(col)最小 最大值
sum(col)求和
SET NAMES utf8 设置编码
基本查询
select * from biao 条件
select * from biao where id=1 结果字段不重复
select distinct id from biao 排序,默认升序asc,降序desc
select * from biao order by id; select * from biao order by id desc ,time asc; 分组,having 限定条件
select * from biao group by sex; select * from biao group by sex having; 查询条数
select * from biao limit 4 返回4条 select * from biao 4,3 返回3条,从第5条记录开始 内连接两个功能相同
select a,b,c from A inner join B on A.id = B.id; select a,b,c from A,B where A.id=B.id; 左右连接
select * from A left join B on A.id=B.id; select * from A right join B on A.id=B.id; 子查询
select id from Table where id2 in(select id3 from Table2) 合并结果集
select * from A union all select * from B select * from A union select * from B 去重复 表或字段别名
select id as ID from A as a
插入
insert into Table(id,name) values (null,'Li') ;插入数据 insert into T(id,name) values (null,'Li'),(null,"Zhao"); insert into T values (null,"Li",null,"数据");插入所有列 insert into T(id,name) select id,name from T2; 查询插入 insert ignore into Table(id,name) values (null,'Li') ; 唯一索引插入 有效防止重复数据 修改
update T set name='Li' where id=1; 更新 update t set num=num+1 where id=1 自动加一 update T left join T1 on T.id=T1.id set u='1',u1='2' where id=1;多表更新 update T set user=replace(user,'a','a1') 替换表字段 删除
delete from T where id =1;删除 delete from T where id in(1,2,3);删除多条 清空
truncate table test常用的查询：
select * from ims_rank where DATE_SUB(CURDATE(),INTERVAL 7 DAY) <= date(createtime); 七天之前数据 30天 select * from ims_rank where to_days(createtime) =to_days(now()); 今天数据 select * from ims_rank where TO_DAYS( NOW( ) ) -TO_DAYS( createtime) <= 1 昨天今天数据 select * from ims_rank where DATE_FORMAT( createtime,'%Y%m' ) = DATE_FORMAT( CURDATE( ) , '%Y%m' )本月 select * from ims_rank where PERIOD_DIFF( date_format(now( ) , '%Y%m' ) , date_format( createtime, '%Y%m' ) ) =1 上月 select * from ims_rank where YEARWEEK(date_format(createtime,'%Y-%m-%d')) =YEARWEEK(now()); 本周(第一天星期日) select * from ims_rank where YEARWEEK(date_format(createtime,'%Y-%m-%d')) = YEARWEEK(now())-1; 上周数据