1.insert
insert into <表名>(字段名) values (值)
例:
create table test (
id int(4) not null auto_increment,
name char(20) not null,
primary key(id)
) ;
1)按列名插入
2)不指定列名,则需按顺序插入
3)支持批量插入(可作为研发优化点)
4)删除数据
2.备份数据库
dump把数据库操作以SQL语句保存下来,逻辑备份
3.select(研发优化,最好不用*)
select from where
限制返回行数(默认从第0行开始):
关联表select:
4.explain查询SQL执行状态
5.修改表中数据
update 表名 set 字段=新值,...where 条件()
如果update时没有指定where条件,则整个表都会被更新,此时则要做数据恢复,可能会丢失新的数据,则需执行增量恢复:
mysql -uroot -p456 oldboy </opt/oldboy_bak.sql
执行增量恢复的条件,log-bin需打开,生产中需对此文件备份:
此参数改完需重启数据库:
做一次Update操作后,会生成文件:
该文件是二进制文件,需用mysqlbinlog打开,即可以看到相关的update语句
若想恢复到此binlog文件时的数据库状态,修复过程简易版:
1)将该文件从data目录下备份到其他目录:
cp mysqlbin_oldboy.000001 /opt/
2)mysqladmin -uroot -p456 flush-log 切割,可以看到data下此时变成两个binlog文件
3)恢复
mysql -uroot -p456 oldboy </opt/oldboy_bak.sql
此时在数据库外面可查看恢复情况:
mysql -uroot -p456 -e "select * from oldboy.test";
此时恢复的数据库应缺少dump到发生错误操作之间的数据,要想恢复到00001文件的时间点:
mysqlbinlog mysql
mysqlbinlog -d oldboy mysqlbin_oldboy.00001 >bin.sql
mysql -uroot -p456 oldboy <bin.sql
防止数据库误操作:
1、mysql帮助说明
[oldboy_c64 ~]# mysql --help|grep dummy
-U, --i-am-a-dummy Synonym for option --safe-updates, -U.
i-am-a-dummy FALSE
在mysql命令加上选项-U后,当发出没有WHERE或LIMIT关键字的UPDATE或DELETE时,mysql程序就会拒绝执行
2、指定-U登录测试
[oldboy_c64 ~]# mysql -uroot -poldboy123 -S /data/3306/mysql.sock -U
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 14
Server version: 5.5.32-log MySQL Community Server (GPL)
Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement.
mysql> delete from oldboy.student;
ERROR 1175 (HY000): You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
mysql> quit
Bye
提示:不加条件无法删除,目的达到。
3、做成别名防止老大和DBA误操作
[oldboy_c64 ~]# alias mysql=‘mysql -U‘
[oldboy_c64 ~]# mysql -uroot -poldboy123 -S /data/3306/mysql.sock
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 15
Server version: 5.5.32-log MySQL Community Server (GPL)
Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement.
mysql> delete from oldboy.student;
ERROR 1175 (HY000): You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
mysql> delete from oldboy.student where Sno=5;
Query OK, 1 row affected (0.02 sec)
mysql> quit
Bye
[oldboy_c64 ~]# echo "alias mysql=‘mysql -U‘" >>/etc/profile
[oldboy_c64 ~]# . /etc/profile
[oldboy_c64 ~]# tail -1 /etc/profile
alias mysql=‘mysql -U‘
结论:
在mysql命令加上选项-U后,当发出没有WHERE或LIMIT关键字的UPDATE或DELETE时,mysql程序拒绝执行
6.删除表中数据
delete from 表 where 条件;相当于逻辑清除,按行删
truncate table 表; 清空表中所有内容,比delete更快,相当于清空物理文件
7.增删改表的字段
alter table 表名 add字段 类型 其他;
alter table test add age int(4) after name;
修改:change、modify
rename table test to test1;
原文地址:https://www.cnblogs.com/wangke2017/p/9640906.html