【mysql】工作中mysql常用命令及语句

1.查看mysql版本号

MySQL [release_test_oa]> select version();
+------------+
| version()  |
+------------+
| 5.6.27-log |
+------------+
1 row in set (0.00 sec)

或者

MySQL [release_test_oa]> status;
--------------
mysql  Ver 15.1 Distrib 5.5.44-MariaDB, for Linux (x86_64) using readline 5.1

Connection id:        1044533
Current database:    release_test_oa
Current user:        root@localhost
SSL:            Not in use
Current pager:        stdout
Using outfile:        ''
Using delimiter:    ;
Server:            MySQL
Server version:        5.6.27-log Source distribution

2.连接本地mysql

 mysql -uroot -p   或者  mysql -h127.0.0.1 -uroot -p

连接远程mysql

mysql -u root -p -h 192.168.1.2

3.导出本地数据库某张表(比如导出数据中的USERS表)   回车后要输入数据库密码

mysqldump  databases  -u root -p --tables USERS>/usr/tmp/users.sql

4.导出远程数据库某张表(USERS表)   回车后要输入数据库密码

mysqldump -h192.168.79.206 -p3306  databases  -u root -p --tables USERS>/usr/tmp/users.sql

5.表名重命名

RENAME TABLE USERS TO USERS_BAK

6.查看表索引信息

show index from tables;   或者 show keys from tables; 两个命令输出都一样

7.复制表命令

原表是vistor

create table vistor_two like vistor;             这个会把原表的索引信息带过去,   用上面查看索引命令可以查看的到 ,但只是复制表结构；

create table vistor_three select * from vistor;  这个不会把原表的索引信息带过去，会把数据复制过去； (最好不要用这个，之前工作中因为表没自增主键导致程序插入的数据主键字段id值都为0)

8.新增字段

 alter table tablename  add new_ziduan int(4) default '0';

9.删除字段

alter table tablename  drop column;

10.删除表数据

delete from tablename ； 或者 truncate tablename ；   第一个删除会有删除记录，误删可以通过日志恢复记录；truncate是删除了旧表，重新创建了这个表，之前所有的状态都相当于新表；

11.复制表部分字段数据到另一张表 (同字段类型)

 insert into tables_new (ID,BYNAME,STATUS) select ID,BYNAME,STATUS from tables_old;

12.查看表字段

show columns from tablename;

13.查看表状态

show table status;  显示所有的表
show table status from database_name like 'task%'; 显示数据库database_name中表名以task开头的表。

14.查看表有多少个字段

select count(*) from information_schema.COLUMNS where TABLE_SCHEMA='数据库名' and table_name='表名'

15.修改mysql登录用户密码

use mysql； 选中mysql库
update user set password=password('你要修改的密码') where user='用户名';
然后在刷新权限生效
flush privileges；

　可用select length(password('123'))察看加密后密码长度

16.查看mysql端口号

mysql> show global variables like 'port';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| port          |   |
+---------------+-------+

17.查看临时表

mysql> SHOW STATUS LIKE 'created_tmp%';
+-------------------------+-------+
| Variable_name           | Value |
+-------------------------+-------+
| Created_tmp_disk_tables |      |
| Created_tmp_files       |      |
| Created_tmp_tables      |      |
+-------------------------+-------+

18.查看引擎

mysql>  SHOW ENGINES;
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine             | Support | Comment                                                        | Transactions | XA   | Savepoints |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        |
| FEDERATED          | NO      | Federated MySQL storage engine                                 | NULL         | NULL | NULL       |
| MRG_MYISAM         | YES     | Collection of identical MyISAM tables                          | NO           | NO   | NO         |
| BLACKHOLE          | YES     | /dev/null storage engine (anything you write to it disappears) | NO           | NO   | NO         |
| MyISAM             | YES     | MyISAM storage engine                                          | NO           | NO   | NO         |
| MEMORY             | YES     | Hash based, stored in memory, useful for temporary tables      | NO           | NO   | NO         |
| CSV                | YES     | CSV storage engine                                             | NO           | NO   | NO         |
| ARCHIVE            | YES     | Archive storage engine                                         | NO           | NO   | NO         |
| PERFORMANCE_SCHEMA | YES     | Performance Schema                                             | NO           | NO   | NO         |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+

19.查看字符集

mysql> SHOW COLLATION;
+----------------------------+----------+-----+---------+----------+---------+
| Collation                  | Charset  | Id  | Default | Compiled | Sortlen |
+----------------------------+----------+-----+---------+----------+---------+
| armscii8_bin               | armscii8 |   |         | Yes      |        |
| armscii8_general_ci        | armscii8 |   | Yes     | Yes      |        |
| ascii_bin                  | ascii    |   |         | Yes      |        |
| ascii_general_ci           | ascii    |   | Yes     | Yes      |        |
| big5_bin                   | big5     |   |         | Yes      |        |
| big5_chinese_ci            | big5     |    | Yes     | Yes      |        |
| binary                     | binary   |   | Yes     | Yes      |        |
| cp1250_bin                 | cp1250   |   |         | Yes      |        |
| cp1250_croatian_ci         | cp1250   |   |         | Yes      |        |
| cp1250_czech_cs            | cp1250   |   |         | Yes      |        |
| cp1250_general_ci          | cp1250   |   | Yes     | Yes      |        |
| cp1250_polish_ci           | cp1250   |   |         | Yes      |        |

20.查看线程使用的情况

mysql> SHOW STATUS LIKE 'threads%';
+-------------------+-------+
| Variable_name     | Value |
+-------------------+-------+
| Threads_cached    |      |
| Threads_connected |      |
| Threads_created   |      |
| Threads_running   |      |
+-------------------+-------+

 21.启动时候指定用户身份

[root@localhost bin]# ./mysqld --user=mysql    指定用mysql用户身份

22.查看表字段及注释

show full fields  from table_name;

 23.修改表引擎

ALTER TABLE table_name ENGINE=InnoDB;   #将表存储引擎修改为innodb

24.重置autoIncrement的值

ALTER TABLE table_name AUTO_INCREMENT = 1;

 25.索引创建 删除 查看

CREATE UNIQUE INDEX index_name ON table_name(字段名)   创建唯一索引
DROP INDEX index_name ON talbe_name　　　　　　　　　　　 删除索引
show index from  table_name                           查看表索引信息

26.查询当前MySQL本次启动后的运行统计时间

mysql> show status like 'uptime';

+---------------+--------+
| Variable_name | Value  |
+---------------+--------+
| Uptime        | 140459 |
+---------------+--------+

27.查看是否有表锁住

show OPEN TABLES where In_use > 0;

 28.查看查询进程

show processlist;

如果不进入mysql命令行也可以进入mysql/bin目录下输入mysqladmin processlist。

如果没有SUPER权限，则只能看到自己发起的线程， 否则可以看到全部的线程。

 29.返回不重复数据

SELECT DISTINCT user_name,vistor_username  FROM KY_FEED_VISTOR WHERE user_name='shenhy'  

单独的distinct只能放在开头 而且distinct()里面只能包含一个字段

SELECT *  FROM KY_FEED_VISTOR WHERE user_name='shenhy'  GROUP BY user_name, vistor_username  ORDER BY  vistor_time DESC

30.创建一个新表且新表的结构与查询的表的结构是一样，不过没有索引

create newTable newtable as select * from oldTable where 1=0; 

 31.模糊查询表

SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE table_schema = '数据库名' AND TABLE_NAME LIKE '表名%'

如果想生成清空多个表语句，也可以按照下面方法生成对多张表的truncate语句。

select CONCAT('truncate TABLE ',table_schema,'.',TABLE_NAME, ';') from INFORMATION_SCHEMA.TABLES where  table_schema = '数据库名' AND TABLE_NAME LIKE '表名%';

32.复制表信息到另一张表

从一个表中复制所有的列插入到另一个已存在的表中：
INSERT INTO 表名 SELECT * FROM 目标表名;
或者只复制希望的列插入到另一个已存在的表中：
INSERT INTO 表名 (column_name(s)) SELECT column_name(s) FROM 目标表名;

 33.获取字段后几个字符

 34.mysql  select  update语句

　　当我们需要从select结果中去update时候，一般我们会想到update table  set a= 1 where id in (select id from table), 但是这样是不行的，如下。

update select 语句需要使用inner join

update kaoqin_grant_record inner join (SELECT id FROM kaoqin_grant_record WHERE invalid_time <= '2019-11-01' AND  balance_type = 5 AND operator_type = 1 AND is_has_cleand = 0) AS child on kaoqin_grant_record.id =child.id set kaoqin_grant_record.is_has_cleand = 1

 35.获取所有表的行数

SELECT table_name, table_rows FROM information_schema.tables WHERE table_schema = 'hrms' ORDER BY table_rows desc

持续更新........