[1] View mysql

ps -ef|grep mysql

root     17659     1  0  2011 ?        00:00:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --socket=/var/lib/mysql/mysql.sock --log-error=/var/log/mysqld.log --pid-file=/var/run/mysqld/mysqld.pid   

mysql    17719 17659  0  2011 ?        03:14:57 /usr/libexec/mysqld --basedir=/usr --datadir=/var/lib/mysql --user=mysql --pid-file=/var/run/mysqld/mysqld.pid --skip-external-locking --socket=/var/lib/mysql/mysql.sock  

usr/bin/mysql Means: mysql Running Path 
var/lib/mysql Means: mysql Storage Path of Database Files 
usr/lib/mysql Means: mysql Installation Road

[2] Connect to the database

mysql -uroot[username] -p
Enter password:

[3] mysql service

service mysqld stop ;
service mysqld start;
After service restart, it may be out of order. tomcat needs to be restarted!!!

If there is no installation, prompt:

[root@localhost ~]# service mysqld start 
mysqld:Unrecognized services

Check if the service has been added to linux (if installed, it will be prompted as follows)

[root@localhost ~]# chkconfig --list mysqld 
mysqld          0:Close  1:Close  2:Close  3:Close  4:Close  5:Enable  6:Close

If there is no installation, prompt:

[root@localhost ~]# chkconfig --list mysqld 
Error reading information in mysqld service, no file or directory

Once you start the service, you can check whether the server is running or not.

[root@localhost ~]# ps -el | grep mysqld 
4 S     0  1796     1  0  85   0 -  1513 wait   ?        00:00:00 mysqld_safe 
4 S    27  1856  1796  0  78   0 - 34055 -      ?        00:00:00 mysqld 
[root@localhost ~]# 

If you see it, it means that the server is installed ~~

[4] Backup database

mysqldump basic grammar:
　　mysqldump -u username -p dbname table1 table2 ...-> BackupName.sql
　　
Among them:
The dbname parameter represents the name of the database.
The table1 and table2 parameters indicate the name of the table that needs to be backed up, and if it is empty, the whole database will be backed up.
BackupName.sql parameter table designs the name of the backup file, which can be preceded by an absolute path. Usually the database is divided into a file with the suffix sql.

For example, backup cloudoa database to the current path:
mysqldump -uroot -p cloudoa >./backup.sql

[5] Check and repair database tables

If the following prompt appears:

 Table './hb_cloudoa/tb_xmpp_notice' is marked as crashed and should be repaired

Operation:

Login: mysqlcheck-u root-p hb_cloudoa
 Enter password:

Then add the auto-repair parameter to repair automatically.

It's better to back up the database before repairing it (as shown in the fourth above):

mysqldump -u root -p hb_cloudoa > hb_cloudoa.sql
Enter password:

[Repair]

mysqlcheck -u root -p hb_cloudoa --auto-repair
Enter password:

[6] View File Installation Path

whereis mysql

[root@YCOffcie /]# whereis mysql
mysql: /usr/bin/mysql /usr/lib64/mysql /usr/include/mysql /usr/local/mysql /usr/share/mysql /usr/share/man/man1/mysql.1.gz

[7] Query the path of the running file (folder address)

which mysql

[root@YCOffcie /]# which mysql
/usr/bin/mysql