mysql的基本操作

 /*

         Mysql基础操作(优化)

         @auther: luowen

         @time: 2013-07-26

   



     1.mysql复制表机构和表数据

         create table t1 like t2; 

         insert into t1 select * from t2;

     2.mysql创建索引

         method 1:

             increate [unique] [index] [primary key] indexName on t1(name);

             show index from t1;

             drop index [unique] [index] [primary key]indexName on t1;    

        method 2:

            alter table t1 add [index][unique][primary key] indexName (column);

            alter table t1 drop [index][unique][primary key] indexName;

     3.mysql 视图

         create view v_t1 as select * from t1 where id >　3;

         drop view v_t1;

     4.mysql 内置函数

         [字符串函数]

             1.连接函数

                 concat select concat('luowe','wen') as luowen;

             2.大小写转换

                 lcase select lcase('SDFSADF') as demo

                 ucase select ucase('asdfsadf') as demo2

             3.长度 length

                 length select length('sdfsadfsadf');

             4.去空

                 ltrim select ltrim('           sadfsdf')

                 rtrim select rtrim('asdfsaf       ')

             5.重复

                 repleat select repleat('xx',10)

             6.替代

                 replace select replace('linux is very good','linux','php') ;

             7.截取

                 substr select substr('linux is very good',pos,length);   // pos 是从1开始

             8.生成空格

                 space select space(10); select concat(space(10),'linux'); //在linux左侧添加了10个空格

         [数学函数]

             1.二进制函数

                 bin select bin(10);

             2.取整

                 ceiling select ceiling(2.5)     //3

                 floor select floor(2.5) //2

             3.最大最小

                 max max(col);    //聚合使用

                 min min(col);

             4.平方根

                 sqrt select sqrt(2);

             5.随机数

                 rand select rand(count); //count 选出几个 配合order by 可是实现随机排序

         [日期函数]

             1.curdate //当前时间

             2.curtime

             3.now();

             4.unix_timestamp

             5.week

             6.year

             7.datediff('日期1','日期2') //计算中间差了几天





    5: mysql 的预处理

        prepare preTable from "select * from t2 where id > ?";



        set @i=3;



        execute preTable using @i; //@i替代了prepare 语句中的?号



        drop prepare preTable //删除预处理

    6:mysql 事务(MyISAM不支持事务,innoDB支持)

        set autocommit = 0; //打开事务

        //alter table t2 engine innodb;//修改表引擎

        delete from t2 where id < 1;

        savepoint p1

        delect form t2 where id < 3;

        savepoint p2;



        rollback to p2 //还原到p2的点



        rollback    //回滚

        commit         //提交

    7:mysql 存储

        procedure   //一个小段的程序

        \d //       //将存储设置定界符

        create procedure p1()

            begin

                set @i = 3

                    while @i <= 100 do

                    insert into t2(name) values(concat('user',@i));

                    end while;

            end//

        show create procedure p2   //查看存储

        call p2   //呼叫执行p2

        drop prcedure p2

    8:mysql 触发器

        trigger

            \d //      //修改定界符

            create trigger tg1 before insert on t1 for each row

                begin

                    insert into t2(id) value(new.id);

                end

    9:auto_increment 恢复1

        truncate table; //已经恢复1

        delete from table //没有恢复

        alter table auto_increment = 1;