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mysql的基本用法

Jun 07, 2016 pm 03:01 PM
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欢迎进入Linux社区论坛,与200万技术人员互动交流 >>进入 创建数据库:create database [if not exist]name [character set 编码方式 collate 校对规则] 显示库的创建信息:show create database name 数据库的删除:drop database [if exist]name 备份数据

欢迎进入Linux社区论坛,与200万技术人员互动交流 >>进入

  创建数据库:create database [if not exist]name [character set 编码方式 collate 校对规则]

  显示库的创建信息:show create database name

  数据库的删除:drop database [if exist]name

  备份数据库:mysqldump -u用户名 -p数据库名>(路径)文件名。sql(windows命令、脚本文件,要退出sql命令窗口quit)

  数据库恢复(1):Source 文件名。sql(sql命令)

  1、创建库 create database name;

  2、恢复数据 Source (加路径)文件。sql

  数据库恢复(2):(上面步骤2改为)mysqldump -u用户名 -p数据库名

  查看表的结构:desc table_name;

  更改表的名字:rename table table_name to new_name;

  更改表的列名:alter table table_name change column name new_name 类型;

  1、插入失败的解决方案:

  show variables like 'chara%'

  set character_set_client=gb2312

  显示失败后的解决方案:set character_set_results=gb2312(只对这次有效窗口关闭后失效,永久有效应该改配置文件)

  修改表中数据:update table_name set col_name=value where …;

  删除一条记录:delete from table_name where …;

  不能删除某一列的值,也不能删除表;删除时应注意与其他表的参照完整性问题

  truncate 也可以删除表中的记录(先摧毁表再重建表的结构)

  查询语句:select [distinct](过滤掉重复数据) col1,col2 from table_name;

  可以多数据进行运算:select col_name+10 from table_name;select(col1+col2+col3)from table_name

  使用别名进行显示:select(col1+col2+col3) as 总数 from table_name(不用as也可以)

  模糊查询中%代表一个或多个字符_代表一个字符

  order by 放在select语句后面进行排序 …order by col_name asc/desc;

  count统计:select count(*) from table_name;统计有多少行

  sum合计函数:select sum(列名) from table_name;统计该列数据总和

  AVG返回平均值

  Max/min返回最大值最小值

  group by:对列进行分组

  有合计函数时使用having子句过滤where放在最后 而不能用where

  定义主键(primary key)不允许为空不允许重复

  定义主键自动增长 auto_increment

  定义唯一性:unique

  非空:not null;

  定义外键约束:constraint ordersid_FK foreign key (ordersid) references others(id);

mysql的基本用法

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