在启动mysql时报下列错误
[root@mysqld2 ~]# service mysql.server start
Starting MySQL......................................The server quit without updating PID file (/var/lib/mysql/mysqld2.clvn.com.cn.pid). [失败]
解决方法
查看日志文件
[root@mysqld1 mysql]# tail /var/log/mysqld.log
2014-05-09 22:08:10 3483 [Note] NDB: Changed global value of binlog_format from STATEMENT to MIXED
2014-05-09 22:08:46 3483 [Warning] NDB: server id set to zero - changes logged to bin log with server id zero will be logged with another server id by slave mysqlds
2014-05-09 22:08:46 3483 [Note] Starting Cluster Binlog Thread
2014-05-09 22:08:46 3483 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 6f59371c-d783-11e3-ac36-000c2971b28f.
2014-05-09 22:08:46 3483 [Note] Server hostname (bind-address): '*'; port: 3306
2014-05-09 22:08:46 3483 [Note] IPv6 is available.
2014-05-09 22:08:46 3483 [Note] - '::' resolves to '::';
2014-05-09 22:08:46 3483 [Note] Server socket created on IP: '::'.
2014-05-09 22:08:46 3483 [ERROR] Fatal error: Can't open and lock privilege tables: Table 'mysql.user' doesn't exist
140509 22:08:46 mysqld_safe mysqld from pid file /var/lib/mysql/mysqld1.clvn.com.cn.pid ended
解决方法
[root@mysqld1 mysql]# scripts/mysql_install_db --user=mysql
Installing MySQL system tables...2014-05-09 22:51:12 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2014-05-09 22:51:12 3564 [Note] InnoDB: Using atomics to ref count buffer pool pages
2014-05-09 22:51:12 3564 [Note] InnoDB: The InnoDB memory heap is disabled
2014-05-09 22:51:12 3564 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2014-05-09 22:51:12 3564 [Note] InnoDB: Compressed tables use zlib 1.2.3
2014-05-09 22:51:12 3564 [Note] InnoDB: Using Linux native AIO
2014-05-09 22:51:12 3564 [Note] InnoDB: Using CPU crc32 instructions
2014-05-09 22:51:12 3564 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2014-05-09 22:51:12 3564 [Note] InnoDB: Completed initialization of buffer pool
2014-05-09 22:51:12 3564 [Note] InnoDB: Highest supported file format is Barracuda.
2014-05-09 22:51:12 3564 [Note] InnoDB: 128 rollback segment(s) are active.
2014-05-09 22:51:12 3564 [Note] InnoDB: Waiting for purge to start
2014-05-09 22:51:13 3564 [Note] InnoDB: 5.6.17 started; log sequence number 1626007
2014-05-09 22:51:13 3564 [Note] Binlog end
2014-05-09 22:51:13 3564 [Note] InnoDB: FTS optimize thread exiting.
2014-05-09 22:51:13 3564 [Note] InnoDB: Starting shutdown...
2014-05-09 22:51:14 3564 [Note] InnoDB: Shutdown completed; log sequence number 1626017
OK
Filling help tables...2014-05-09 22:51:14 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2014-05-09 22:51:14 3588 [Note] InnoDB: Using atomics to ref count buffer pool pages
2014-05-09 22:51:14 3588 [Note] InnoDB: The InnoDB memory heap is disabled
2014-05-09 22:51:14 3588 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2014-05-09 22:51:14 3588 [Note] InnoDB: Compressed tables use zlib 1.2.3
2014-05-09 22:51:14 3588 [Note] InnoDB: Using Linux native AIO
2014-05-09 22:51:14 3588 [Note] InnoDB: Using CPU crc32 instructions
2014-05-09 22:51:14 3588 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2014-05-09 22:51:14 3588 [Note] InnoDB: Completed initialization of buffer pool
2014-05-09 22:51:14 3588 [Note] InnoDB: Highest supported file format is Barracuda.
2014-05-09 22:51:14 3588 [Note] InnoDB: 128 rollback segment(s) are active.
2014-05-09 22:51:15 3588 [Note] InnoDB: Waiting for purge to start
2014-05-09 22:51:15 3588 [Note] InnoDB: 5.6.17 started; log sequence number 1626017
2014-05-09 22:51:15 3588 [Note] Binlog end
2014-05-09 22:51:15 3588 [Note] InnoDB: FTS optimize thread exiting.
2014-05-09 22:51:15 3588 [Note] InnoDB: Starting shutdown...
2014-05-09 22:51:16 3588 [Note] InnoDB: Shutdown completed; log sequence number 1626027
OK
To start mysqld at boot time you have to copy
support-files/mysql.server to the right place for your system
PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER !
To do so, start the server, then issue the following commands:
./bin/mysqladmin -u root password 'new-password'
./bin/mysqladmin -u root -h mysqld1.clvn.com.cn password 'new-password'
Alternatively you can run:
./bin/mysql_secure_installation
which will also give you the option of removing the test
databases and anonymous user created by default. This is
strongly recommended for production servers.
See the manual for more instructions.
You can start the MySQL daemon with:
cd . ; ./bin/mysqld_safe &
You can test the MySQL daemon with mysql-test-run.pl
cd mysql-test ; perl mysql-test-run.pl
Please report any problems at http://bugs.mysql.com/
The latest information about MySQL is available on the web at
http://www.mysql.com
Support MySQL by buying support/licenses at http://shop.mysql.com
WARNING: Found existing config file ./my.cnf on the system.
Because this file might be in use, it was not replaced,
but was used in bootstrap (unless you used --defaults-file)
and when you later start the server.
The new default config file was created as ./my-new.cnf,
please compare it with your file and take the changes you need.
[root@mysqld1 mysql]# ./bin/mysqld_safe &
[1] 3612
[root@mysqld1 mysql]# 140509 22:51:29 mysqld_safe Logging to '/usr/local/mysql/data/mysqld1.clvn.com.cn.err'.
140509 22:51:29 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/data
查看mysql.server的状态信息
[root@mysqld1 ~]# service mysql.server start
Starting MySQL. [确定]
问题解决

ACID属性包括原子性、一致性、隔离性和持久性,是数据库设计的基石。1.原子性确保事务要么完全成功,要么完全失败。2.一致性保证数据库在事务前后保持一致状态。3.隔离性确保事务之间互不干扰。4.持久性确保事务提交后数据永久保存。

MySQL既是数据库管理系统(DBMS),也与编程语言紧密相关。1)作为DBMS,MySQL用于存储、组织和检索数据,优化索引可提高查询性能。2)通过SQL与编程语言结合,嵌入在如Python中,使用ORM工具如SQLAlchemy可简化操作。3)性能优化包括索引、查询、缓存、分库分表和事务管理。

MySQL使用SQL命令管理数据。1.基本命令包括SELECT、INSERT、UPDATE和DELETE。2.高级用法涉及JOIN、子查询和聚合函数。3.常见错误有语法、逻辑和性能问题。4.优化技巧包括使用索引、避免SELECT*和使用LIMIT。

MySQL是一种高效的关系型数据库管理系统,适用于存储和管理数据。其优势包括高性能查询、灵活的事务处理和丰富的数据类型。实际应用中,MySQL常用于电商平台、社交网络和内容管理系统,但需注意性能优化、数据安全和扩展性。

SQL和MySQL的关系是标准语言与具体实现的关系。1.SQL是用于管理和操作关系数据库的标准语言,允许进行数据的增、删、改、查。2.MySQL是一个具体的数据库管理系统,使用SQL作为其操作语言,并提供高效的数据存储和管理。

InnoDB使用redologs和undologs确保数据一致性和可靠性。1.redologs记录数据页修改,确保崩溃恢复和事务持久性。2.undologs记录数据原始值,支持事务回滚和MVCC。

EXPLAIN命令的关键指标包括type、key、rows和Extra。1)type反映查询的访问类型,值越高效率越高,如const优于ALL。2)key显示使用的索引,NULL表示无索引。3)rows预估扫描行数,影响查询性能。4)Extra提供额外信息,如Usingfilesort提示需要优化。

Usingtemporary在MySQL查询中表示需要创建临时表,常见于使用DISTINCT、GROUPBY或非索引列的ORDERBY。可以通过优化索引和重写查询避免其出现,提升查询性能。具体来说,Usingtemporary出现在EXPLAIN输出中时,意味着MySQL需要创建临时表来处理查询。这通常发生在以下情况:1)使用DISTINCT或GROUPBY时进行去重或分组;2)ORDERBY包含非索引列时进行排序;3)使用复杂的子查询或联接操作。优化方法包括:1)为ORDERBY和GROUPB


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