mysql常用操作
查看mysql数据库有哪些库：mysql> show databases;
切换数据库：mysql> use discuz
查看当前在哪个数据库里面：mysql> select database();
查看用户：mysql> select user();
查看版本：mysql> select version();
库里面是表，表里面是行，行里面是字段
mysql> use discuz
mysql> show tables;（查看有哪些表）
mysql> desc pre_ucenter_vars;（查看pre_ucenter_vars这个表有哪些字段）
查看表的建表语句，这个表怎么创建的：mysql> show create table pre_ucenter_vars\G;
mysql> create database aming;(创建aming这个库）
mysql> use aming
创建一个表，并且表里有几个字段，int和char是格式，4和40是长度
mysql> create table tb1 (`id` int(4),`name` char(40)) ENGINE=MYISAM DEFAULT CHARSET=gbk;
mysql> show tables;
Current database: aming
+-----------------+
| Tables_in_aming |
+-----------------+
| tb1 |
+-----------------+
1 row in set (0.00 sec)
mysql> desc tb1;
Current database: aming
+-------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id | int(4) | YES | | NULL | |
| name | char(40) | YES | | NULL | |
+-------+----------+------+-----+---------+-------+
2 rows in set (0.00 sec)
mysql> show create table tb1\G;
Current database: aming
*************************** 1. row ***************************
Table: tb1
Create Table: CREATE TABLE `tb1` (
`id` int(4) DEFAULT NULL,
`name` char(40) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=gbk
1 row in set (0.00 sec)
这个表建完之后意味着要在里面插入一些数据
mysql> insert into tb1 values(1,'aming');
mysql> select * from tb1;
Current database: aming
+------+-------+
| id | name |
+------+-------+
| 1 | aming |
+------+-------+
1 row in set (0.00 sec)
可以继续插入数据：mysql> insert into tb1 values(2,'linux');
mysql> select * from tb1;
+------+-------+
| id | name |
+------+-------+
| 1 | aming |
| 2 | linux |
+------+-------+
2 rows in set (0.01 sec)
也可以单独插入
mysql> insert into tb1 (`id`) values(2);
mysql> select * from tb1;
Current database: aming
+------+-------+
| id | name |
+------+-------+
| 1 | aming |
| 2 | linux |
| 2 | NULL |
+------+-------+
3 rows in set (0.00 sec)
mysql> insert into tb1 (`name`) values('55');
mysql> select * from tb1;
Current database: aming
+------+-------+
| id | name |
+------+-------+
| 1 | aming |
| 2 | linux |
| 2 | NULL |
| NULL | 55 |
+------+-------+
4 rows in set (0.01 sec)
更新一个数据
mysql> update tb1 set id=5 where name='55';
mysql> select * from tb1;
删除一行：mysql> delete from tb1 where name='55';
mysql> select * from tb1;
+------+-------+
| id | name |
+------+-------+
| 1 | aming |
| 2 | linux |
| 2 | NULL |
+------+-------+
3 rows in set (0.00 sec)
清空一个表（表里面数据很多，可以清除里面数据)
mysql> truncate table aming.tb1;（aming是库，tb1是表名)
mysql> select * from tb1;
Empty set (0.00 sec)
mysql> drop table tb1;（干掉一个表）
Table 'aming.tb1' doesn't exist(会提示不存在）
授权
mysql> grant all on discuz.* to 'user1'@'192.168.137.%' idenified by 'qwe'；（%是通配符）
mysql> flush privileges;(刷新权限）
查看当前数据库有哪些队列，可以知道哪些在工作：mysql> show processlist;
+----+------+-----------+-------+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+-------+---------+------+-------+------------------+
| 36 | root | localhost | aming | Query | 0 | NULL | show processlist |
+----+------+-----------+-------+---------+------+-------+------------------+
1 row in set (0.00 sec)
查看变量：mysql> show variables;
+-----------------------------------------+-------------------------------------------------------------------------------------------+
| Variable_name | Value |
+-----------------------------------------+-------------------------------------------------------------------------------------------+
| auto_increment_increment | 1 |
| auto_increment_offset | 1 |
| autocommit | ON |
| automatic_sp_privileges | ON |
| back_log | 50 |
| basedir | /usr/local/mysql/ |
| big_tables | OFF |
| binlog_cache_size | 32768 |
| binlog_format | STATEMENT |
| bulk_insert_buffer_size | 8388608 |
| character_set_client | latin1 |
| character_set_connection | latin1 |
| character_set_database | latin1 |
| character_set_filesystem | binary |
| character_set_results | latin1 |
| character_set_server | latin1 |
| character_set_system | utf8 |
| character_sets_dir | /usr/local/mysql/share/charsets/ |
| collation_connection | latin1_swedish_ci |
| collation_database | latin1_swedish_ci |
| collation_server | latin1_swedish_ci |
| completion_type | 0 |
| concurrent_insert | 1 |
| connect_timeout | 10 |
| datadir | /data/mysql/ |
| date_format | %Y-%m-%d |
| datetime_format | %Y-%m-%d %H:%i:%s |
| default_week_format | 0 |
| delay_key_write | ON |
| delayed_insert_limit | 100 |
| delayed_insert_timeout | 300 |
| delayed_queue_size | 1000 |
| div_precision_increment | 4 |
| engine_condition_pushdown | ON |
| error_count | 0 |
| event_scheduler | OFF |
| expire_logs_days | 0 |
| flush | OFF |
| flush_time | 0 |
| foreign_key_checks | ON |
| ft_boolean_syntax | + -><()~*:""&| |
| ft_max_word_len | 84 |
| ft_min_word_len | 4 |
| ft_query_expansion_limit | 20 |
| ft_stopword_file | (built-in) |
| general_log | OFF |
| general_log_file | /data/mysql/master.log |
| group_concat_max_len | 1024 |
| have_community_features | YES |
| have_compress | YES |
| have_crypt | YES |
| have_csv | YES |
| have_dynamic_loading | YES |
| have_geometry | YES |
| have_innodb | YES |
| have_ndbcluster | NO |
| have_openssl | NO |
| have_partitioning | YES |
| have_query_cache | YES |
| have_rtree_keys | YES |
| have_ssl | NO |
| have_symlink | YES |
| hostname | master |
| identity | 0 |
| ignore_builtin_innodb | OFF |
| init_connect | |
| init_file | |
| init_slave | |
| innodb_adaptive_hash_index | ON |
| innodb_additional_mem_pool_size | 1048576 |
| innodb_autoextend_increment | 8 |
| innodb_autoinc_lock_mode | 1 |
| innodb_buffer_pool_size | 8388608 |
| innodb_checksums | ON |
| innodb_commit_concurrency | 0 |
| innodb_concurrency_tickets | 500 |
| innodb_data_file_path | ibdata1:10M:autoextend |
| innodb_data_home_dir | |
| innodb_doublewrite | ON |
| innodb_fast_shutdown | 1 |
| innodb_file_io_threads | 4 |
| innodb_file_per_table | OFF |
| innodb_flush_log_at_trx_commit | 1 |
| innodb_flush_method | |
| innodb_force_recovery | 0 |
| innodb_lock_wait_timeout | 50 |
| innodb_locks_unsafe_for_binlog | OFF |
| innodb_log_buffer_size | 1048576 |
| innodb_log_file_size | 5242880 |
| innodb_log_files_in_group | 2 |
| innodb_log_group_home_dir | ./ |
| innodb_max_dirty_pages_pct | 90 |
| innodb_max_purge_lag | 0 |
| innodb_mirrored_log_groups | 1 |
| innodb_open_files | 300 |
| innodb_rollback_on_timeout | OFF |
| innodb_stats_on_metadata | ON |
| innodb_support_xa | ON |
| innodb_sync_spin_loops | 20 |
| innodb_table_locks | ON |
| innodb_thread_concurrency | 8 |
| innodb_thread_sleep_delay | 10000 |
| innodb_use_legacy_cardinality_algorithm | ON |
| insert_id | 0 |
| interactive_timeout | 8 |
| join_buffer_size | 131072 |
| keep_files_on_create | OFF |
| key_buffer_size | 134217728 |
| key_cache_age_threshold | 300 |
| key_cache_block_size | 1024 |
| key_cache_division_limit | 100 |
| language | /usr/local/mysql/share/english/ |
| large_files_support | ON |
| large_page_size | 0 |
| large_pages | OFF |
| last_insert_id | 0 |
| lc_time_names | en_US |
| license | GPL |
| local_infile | ON |
| locked_in_memory | OFF |
| log | OFF |
| log_bin | ON |
| log_bin_trust_function_creators | OFF |
| log_bin_trust_routine_creators | OFF |
| log_error | /data/mysql/master.err |
| log_output | FILE |
| log_queries_not_using_indexes | OFF |
| log_slave_updates | OFF |
| log_slow_queries | ON |
| log_warnings | 1 |
| long_query_time | 1.000000 |
| low_priority_updates | OFF |
| lower_case_file_system | OFF |
| lower_case_table_names | 0 |
| max_allowed_packet | 1048576 |
| max_binlog_cache_size | 18446744073709547520 |
| max_binlog_size | 1073741824 |
| max_connect_errors | 10 |
| max_connections | 151 |
| max_delayed_threads | 20 |
| max_error_count | 64 |
| max_heap_table_size | 16777216 |
| max_insert_delayed_threads | 20 |
| max_join_size | 18446744073709551615 |
| max_length_for_sort_data | 1024 |
| max_prepared_stmt_count | 16382 |
| max_relay_log_size | 0 |
| max_seeks_for_key | 18446744073709551615 |
| max_sort_length | 1024 |
| max_sp_recursion_depth | 0 |
| max_tmp_tables | 32 |
| max_user_connections | 0 |
| max_write_lock_count | 18446744073709551615 |
| min_examined_row_limit | 0 |
| multi_range_count | 256 |
| myisam_data_pointer_size | 6 |
| myisam_max_sort_file_size | 9223372036853727232 |
| myisam_recover_options | OFF |
| myisam_repair_threads | 1 |
| myisam_sort_buffer_size | 67108864 |
| myisam_stats_method | nulls_unequal |
| myisam_use_mmap | OFF |
| net_buffer_length | 16384 |
| net_read_timeout | 30 |
| net_retry_count | 10 |
| net_write_timeout | 60 |
| new | OFF |
| old | OFF |
| old_alter_table | OFF |
| old_passwords | OFF |
| open_files_limit | 1024 |
| optimizer_prune_level | 1 |
| optimizer_search_depth | 62 |
| optimizer_switch | index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on |
| pid_file | /data/mysql/master.pid |
| plugin_dir | /usr/local/mysql/lib/plugin |
| port | 3306 |
| preload_buffer_size | 32768 |
| profiling | OFF |
| profiling_history_size | 15 |
| protocol_version | 10 |
| pseudo_thread_id | 37 |
| query_alloc_block_size | 8192 |
| query_cache_limit | 1048576 |
| query_cache_min_res_unit | 4096 |
| query_cache_size | 16777216 |
| query_cache_type | ON |
| query_cache_wlock_invalidate | OFF |
| query_prealloc_size | 8192 |
| rand_seed1 | |
| rand_seed2 | |
| range_alloc_block_size | 4096 |
| read_buffer_size | 1048576 |
| read_only | OFF |
| read_rnd_buffer_size | 4194304 |
| relay_log | |
| relay_log_index | |
| relay_log_info_file | relay-log.info |
| relay_log_purge | ON |
| relay_log_space_limit | 0 |
| report_host | |
| report_password | |
| report_port | 3306 |
| report_user | |
| rpl_recovery_rank | 0 |
| secure_auth | OFF |
| secure_file_priv | |
| server_id | 1 |
| skip_external_locking | ON |
| skip_networking | OFF |
| skip_show_database | OFF |
| slave_compressed_protocol | OFF |
| slave_exec_mode | STRICT |
| slave_load_tmpdir | /tmp |
| slave_net_timeout | 3600 |
| slave_skip_errors | OFF |
| slave_transaction_retries | 10 |
| slow_launch_time | 2 |
| slow_query_log | ON |
| slow_query_log_file | /data/mysql/slow.log |
| socket | /tmp/mysql.sock |
| sort_buffer_size | 1048576 |
| sql_auto_is_null | ON |
| sql_big_selects | ON |
| sql_big_tables | OFF |
| sql_buffer_result | OFF |
| sql_log_bin | ON |
| sql_log_off | OFF |
| sql_log_update | ON |
| sql_low_priority_updates | OFF |
| sql_max_join_size | 18446744073709551615 |
| sql_mode | |
| sql_notes | ON |
| sql_quote_show_create | ON |
| sql_safe_updates | OFF |
| sql_select_limit | 18446744073709551615 |
| sql_slave_skip_counter | |
| sql_warnings | OFF |
| ssl_ca | |
| ssl_capath | |
| ssl_cert | |
| ssl_cipher | |
| ssl_key | |
| storage_engine | MyISAM |
| sync_binlog | 0 |
| sync_frm | ON |
| system_time_zone | GMT+8 |
| table_definition_cache | 256 |
| table_lock_wait_timeout | 50 |
| table_open_cache | 256 |
| table_type | MyISAM |
| thread_cache_size | 8 |
| thread_handling | one-thread-per-connection |
| thread_stack | 262144 |
| time_format | %H:%i:%s |
| time_zone | SYSTEM |
| timed_mutexes | OFF |
| timestamp | 1438532279 |
| tmp_table_size | 16777216 |
| tmpdir | /tmp |
| transaction_alloc_block_size | 8192 |
| transaction_prealloc_size | 4096 |
| tx_isolation | REPEATABLE-READ |
| unique_checks | ON |
| updatable_views_with_limit | YES |
| version | 5.1.40-log |
| version_comment | MySQL Community Server (GPL) |
| version_compile_machine | x86_64 |
| version_compile_os | unknown-linux-gnu |
| wait_timeout | 8 |
| warning_count | 0 |
+-----------------------------------------+-------------------------------------------------------------------------------------------+
271 rows in set (0.01 sec)
以上这些变量参数都可以在my.cnf里面去定义更改，但是更改后要立即生效需要重启mysql服务。但是mysql服务用着的不想重启，怎么办？比如需要更改max_connections，可以在mysql里面去操作
mysql> set global max_connections=200;
mysql> show variables like 'max_connections';（这里like相当于grep过滤）
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| max_connections | 200 |
+-----------------+-------+
1 row in set (0.00 sec)
但是这样更改后一重启mysql就会失效，可以去my.cnf里面编辑去保存下
查看状态：mysql> show status;
也可以使用like过滤：mysql> show status like '%running';
mysql错误日志
[root@master ~]# cd /data/mysql
[root@master mysql]# ls（master.err就是错误日志）
master.err
修复一个表：比如
mysql> repair table discuz.pre_forum_post;
myisam 和innodb引擎对比 http://www.pureweber.com/article/myisam-vs-innodb/
一台mysql服务器启动多个端口 http://www.lishiming.net/thread-63-1-1.html
什么是事务？事务的特性有哪些？ http://blog.csdn.net/yenange/article/details/7556094
mysql常用引擎 http://c.biancheng.net/cpp/html/1465.html
批量更改表的引擎 http://www.361way.com/change-mysql-engine/1729.html
mysql 二进制日志binlog的模式 http://lihuipeng.blog.51cto.com/3064864/833017
mysql根据binlog恢复指定时间段的数据 http://www.centoscn.com/mysql/2015/0204/4630.html
mysql字符集调整 http://xjsunjie.blog.51cto.com/999372/1355013
使用xtrabackup备份innodb引擎的数据库 http://www.aminglinux.com/bbs/thread-956-1-1.html
innobackupex 备份 Xtrabackup 增量备份 http://www.aminglinux.com/bbs/thread-1012-1-1.html