MySQL中的变量定义

 

@var是用户自定义变量(user defined vars)，@@var是系统变量（system vars），@@var又分成两种：一个是seesion的(local)，一个是server的(global)

 

设置会话变量有如下三种方式：（ 全局同理   session替换成global ）

set session var_name = value;

set @@session.var_name = value;

set var_name = value;

查看一个会话变量也有如下三种方式：

select @@var_name;

select @@session.var_name;

show session variables like "%var%";

 

-----------------------------------------------------------------------------------------------------------------------

 

set  [ global | session ]  transaction isolation level  [ replatable read | read commited | read uncommitted | serializable ]

 

我们知道指定GLOBAL关键字是可以修改全局的设置，用这个方式修改完后，已经存在的连接还不会生效，只有对新建立的连接才会起作用。

而指定SESSION关键字则是只修改当前连接会话的设置，修改完后立即生效，再次连接后会恢复成全局的设置，对其他连接/会话也不起作用。

另外，如果都不指定GLOBAL、SESSION关键字，会发生什么情况呢？

结果是：采用这种方式设置后，本次连接当前事务还未起作用，要到下一个（尚未启动的）新事务才起作用，下一个事务结束后，又将恢复成本次SESSION中原先的设置。

 

如果需要全局调整事务隔离级别，最好是在my.cnf全局配置文件中直接设置好。而如果是要在当前会话中临时调整，可以不要加上SESSION关键字，这样的话，当前事务结束下一个新事务开始后，会自行恢复SESSION的设置，无需人为调整，更加方便。

------------------------------------------------------------------------------------------

根据mysql手册，mysql的变量分为两种：系统变量和用户变量。但是在实际使用中，还会遇到诸如局部变量、会话变量等概念。根据个人感觉，mysql变量大体可以分为四种类型：

一、局部变量。

局部变量一般用在sql语句块中，比如存储过程的begin/end。其作用域仅限于该语句块，在该语句块执行完毕后，局部变量就消失了。

局部变量一般用declare来声明，可以使用default来说明默认值。

例如在存储过程中定义局部变量：

drop procedure if exists add;

create procedure add

(

    in a int,

    in b int

)

begin

    declare c int default 0;

    set c = a + b;

    select c as c;

end;

 

在上述存储过程中定义的变量c就是局部变量

 

二、用户变量。

用户变量的作用域要比局部变量要广。用户变量可以作用于当前整个连接，但是当当前连接断开后，其所定义的用户变量都会消失。

用户变量使用如下(这里我们无须使用declare关键字进行定义，可以直接这样使用):

select @变量名

对用户变量赋值有两种方式，一种是直接用"="号，另一种是用":="号。其区别在于使用set命令对用户变量进行赋值时，两种方式都可以使用；当使用select语句对用户变量进行赋值时，只能使用":="方式，因为在select语句中，"="号被看作是比较操作符。

示例程序如下：

drop procedure if exists math;

create procedure math

(

    in a int,

    in b int

)

begin

    set @var1 = 1;

    set @var2 = 2;

    select @sum:=(a + b) as sum, @dif:=(a - b) as dif;

end;

 

mysql> call math(3, 4);
+------+------+
| sum  | dif  |
+------+------+
|    7 |   -1 | 
+------+------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

mysql> select @var1; //var1为用户变量
+-------+
| @var1 |
+-------+
| 1     | 
+-------+
1 row in set (0.00 sec)

mysql> select @var2; //var2为用户变量
+-------+
| @var2 |
+-------+
| 2     | 
+-------+
1 row in set (0.00 sec)

 

3、会话变量

服务器为每个连接的客户端维护一系列会话变量。在客户端连接时，使用相应全局变量的当前值对客户端的会话变量进行初始化。设置会话变量不需要特殊权限，但客户端只能更改自己的会话变量，而不能更改其它客户端的会话变量。会话变量的作用域与用户变量一样，仅限于当前连接。当当前连接断开后，其设置的所有会话变量均失效。

设置会话变量有如下三种方式：

set session var_name = value;

set @@session.var_name = value;

set var_name = value;

查看一个会话变量也有如下三种方式：

select @@var_name;

select @@session.var_name;

show session variables like "%var%";

 

mysql> show session variables;
+---------------------------------+------------------------------------------------------------+
| Variable_name                   | Value                                                      |
+---------------------------------+------------------------------------------------------------+
| auto_increment_increment        | 1                                                          |
| auto_increment_offset           | 1                                                          |
| automatic_sp_privileges         | ON                                                         |
| back_log                        | 50                                                         |
| basedir                         | /usr/                                                      |
| bdb_cache_size                  | 8388600                                                    |
| bdb_home                        | /var/lib/mysql/                                            |
| bdb_log_buffer_size             | 32768                                                      |
| bdb_logdir                      |                                                            |
| bdb_max_lock                    | 10000                                                      |
| bdb_shared_data                 | OFF                                                        |
| bdb_tmpdir                      | /tmp/                                                      |
| binlog_cache_size               | 32768                                                      |
| 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/share/mysql/charsets/                                 |
| collation_connection            | latin1_swedish_ci                                          |
| collation_database              | latin1_swedish_ci                                          |
| collation_server                | latin1_swedish_ci                                          |
| completion_type                 | 0                                                          |
| concurrent_insert               | 1                                                          |
| connect_timeout                 | 5                                                          |
| datadir                         | /var/lib/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                                                          |
| keep_files_on_create            | OFF                                                        |
| engine_condition_pushdown       | OFF                                                        |
| expire_logs_days                | 0                                                          |
| flush                           | OFF                                                        |
| flush_time                      | 0                                                          |
| ft_boolean_syntax               | + -><()~*:""&|                                             |
| ft_max_word_len                 | 84                                                         |
| ft_min_word_len                 | 4                                                          |
| ft_query_expansion_limit        | 20                                                         |
| ft_stopword_file                | (built-in)                                                 |
| group_concat_max_len            | 1024                                                       |
| have_archive                    | NO                                                         |
| have_bdb                        | YES                                                        |
| have_blackhole_engine           | NO                                                         |
| have_compress                   | YES                                                        |
| have_crypt                      | YES                                                        |
| have_csv                        | NO                                                         |
| have_dynamic_loading            | YES                                                        |
| have_example_engine             | NO                                                         |
| have_federated_engine           | NO                                                         |
| have_geometry                   | YES                                                        |
| have_innodb                     | YES                                                        |
| have_isam                       | NO                                                         |
| have_merge_engine               | YES                                                        |
| have_ndbcluster                 | NO                                                         |
| have_openssl                    | DISABLED                                                   |
| have_ssl                        | DISABLED                                                   |
| have_query_cache                | YES                                                        |
| have_raid                       | NO                                                         |
| have_rtree_keys                 | YES                                                        |
| have_symlink                    | YES                                                        |
| hostname                        | localhost                                                  |
| init_connect                    |                                                            |
| init_file                       |                                                            |
| init_slave                      |                                                            |
| innodb_additional_mem_pool_size | 1048576                                                    |
| innodb_autoextend_increment     | 8                                                          |
| innodb_buffer_pool_awe_mem_mb   | 0                                                          |
| 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_arch_dir             |                                                            |
| innodb_log_archive              | 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_support_xa               | ON                                                         |
| innodb_sync_spin_loops          | 20                                                         |
| innodb_table_locks              | ON                                                         |
| innodb_thread_concurrency       | 8                                                          |
| innodb_thread_sleep_delay       | 10000                                                      |
| interactive_timeout             | 28800                                                      |
| join_buffer_size                | 131072                                                     |
| key_buffer_size                 | 8388600                                                    |
| key_cache_age_threshold         | 300                                                        |
| key_cache_block_size            | 1024                                                       |
| key_cache_division_limit        | 100                                                        |
| language                        | /usr/share/mysql/english/                                  |
| large_files_support             | ON                                                         |
| large_page_size                 | 0                                                          |
| large_pages                     | OFF                                                        |
| lc_time_names                   | en_US                                                      |
| license                         | GPL                                                        |
| local_infile                    | ON                                                         |
| locked_in_memory                | OFF                                                        |
| log                             | OFF                                                        |
| log_bin                         | OFF                                                        |
| log_bin_trust_function_creators | OFF                                                        |
| log_error                       |                                                            |
| log_queries_not_using_indexes   | OFF                                                        |
| log_slave_updates               | OFF                                                        |
| log_slow_queries                | OFF                                                        |
| log_warnings                    | 1                                                          |
| long_query_time                 | 10                                                         |
| low_priority_updates            | OFF                                                        |
| lower_case_file_system          | OFF                                                        |
| lower_case_table_names          | 0                                                          |
| max_allowed_packet              | 1048576                                                    |
| max_binlog_cache_size           | 4294967295                                                 |
| max_binlog_size                 | 1073741824                                                 |
| max_connect_errors              | 10                                                         |
| max_connections                 | 100                                                        |
| max_delayed_threads             | 20                                                         |
| max_error_count                 | 64                                                         |
| max_heap_table_size             | 16777216                                                   |
| max_insert_delayed_threads      | 20                                                         |
| max_join_size                   | 4294967295                                                 |
| max_length_for_sort_data        | 1024                                                       |
| max_prepared_stmt_count         | 16382                                                      |
| max_relay_log_size              | 0                                                          |
| max_seeks_for_key               | 4294967295                                                 |
| max_sort_length                 | 1024                                                       |
| max_sp_recursion_depth          | 0                                                          |
| max_tmp_tables                  | 32                                                         |
| max_user_connections            | 0                                                          |
| max_write_lock_count            | 4294967295                                                 |
| multi_range_count               | 256                                                        |
| myisam_data_pointer_size        | 6                                                          |
| myisam_max_sort_file_size       | 2147483647                                                 |
| myisam_recover_options          | OFF                                                        |
| myisam_repair_threads           | 1                                                          |
| myisam_sort_buffer_size         | 8388608                                                    |
| myisam_stats_method             | nulls_unequal                                              |
| net_buffer_length               | 16384                                                      |
| net_read_timeout                | 30                                                         |
| net_retry_count                 | 10                                                         |
| net_write_timeout               | 60                                                         |
| new                             | OFF                                                        |
| old_passwords                   | ON                                                         |
| open_files_limit                | 1024                                                       |
| optimizer_prune_level           | 1                                                          |
| optimizer_search_depth          | 62                                                         |
| pid_file                        | /var/run/mysqld/mysqld.pid                                 |
| port                            | 3306                                                       |
| preload_buffer_size             | 32768                                                      |
| profiling                       | OFF                                                        |
| profiling_history_size          | 15                                                         |
| protocol_version                | 10                                                         |
| query_alloc_block_size          | 8192                                                       |
| query_cache_limit               | 1048576                                                    |
| query_cache_min_res_unit        | 4096                                                       |
| query_cache_size                | 0                                                          |
| query_cache_type                | ON                                                         |
| query_cache_wlock_invalidate    | OFF                                                        |
| query_prealloc_size             | 8192                                                       |
| range_alloc_block_size          | 2048                                                       |
| read_buffer_size                | 131072                                                     |
| read_only                       | OFF                                                        |
| read_rnd_buffer_size            | 262144                                                     |
| relay_log_purge                 | ON                                                         |
| relay_log_space_limit           | 0                                                          |
| rpl_recovery_rank               | 0                                                          |
| secure_auth                     | OFF                                                        |
| secure_file_priv                |                                                            |
| server_id                       | 0                                                          |
| skip_external_locking           | ON                                                         |
| skip_networking                 | OFF                                                        |
| skip_show_database              | OFF                                                        |
| slave_compressed_protocol       | OFF                                                        |
| slave_load_tmpdir               | /tmp/                                                      |
| slave_net_timeout               | 3600                                                       |
| slave_skip_errors               | OFF                                                        |
| slave_transaction_retries       | 10                                                         |
| slow_launch_time                | 2                                                          |
| socket                          | /var/lib/mysql/mysql.sock                                  |
| sort_buffer_size                | 2097144                                                    |
| sql_big_selects                 | ON                                                         |
| sql_mode                        |                                                            |
| sql_notes                       | ON                                                         |
| 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                | CST                                                        |
| table_cache                     | 64                                                         |
| table_lock_wait_timeout         | 50                                                         |
| table_type                      | MyISAM                                                     |
| thread_cache_size               | 0                                                          |
| thread_stack                    | 196608                                                     |
| time_format                     | %H:%i:%s                                                   |
| time_zone                       | SYSTEM                                                     |
| timed_mutexes                   | OFF                                                        |
| tmp_table_size                  | 33554432                                                   |
| tmpdir                          | /tmp/                                                      |
| transaction_alloc_block_size    | 8192                                                       |
| transaction_prealloc_size       | 4096                                                       |
| tx_isolation                    | REPEATABLE-READ                                            |
| updatable_views_with_limit      | YES                                                        |
| version                         | 5.0.51a                                                    |
| version_bdb                     | Sleepycat Software: Berkeley DB 4.1.24: (January 11, 2008) |
| version_comment                 | Source distribution                                        |
| version_compile_machine         | i386                                                       |
| version_compile_os              | redhat-linux-gnu                                           |
| wait_timeout                    | 28800                                                      |
+---------------------------------+------------------------------------------------------------+
234 rows in set (0.00 sec)

 

 

4、全局变量

全局变量影响服务器整体操作。当服务器启动时，它将所有全局变量初始化为默认值。这些默认值可以在选项文件中或在命令行中指定的选项进行更改。要想更改全局变量，必须具有SUPER权限。全局变量作用于server的整个生命周期，但是不能跨重启。即重启后所有设置的全局变量均失效。要想让全局变量重启后继续生效，需要更改相应的配置文件。

 

要设置一个全局变量，有如下两种方式：

set global var_name = value; //注意：此处的global不能省略。根据手册，set命令设置变量时若不指定GLOBAL、SESSION或者LOCAL，默认使用SESSION

set @@global.var_name = value; //同上

 

要想查看一个全局变量，有如下两种方式：

select @@global.var_name;

show global variables like "%var%";

 

mysql> show global variables;
+---------------------------------+------------------------------------------------------------+
| Variable_name                   | Value                                                      |
+---------------------------------+------------------------------------------------------------+
| auto_increment_increment        | 1                                                          |
| auto_increment_offset           | 1                                                          |
| automatic_sp_privileges         | ON                                                         |
| back_log                        | 50                                                         |
| basedir                         | /usr/                                                      |
| bdb_cache_size                  | 8388600                                                    |
| bdb_home                        | /var/lib/mysql/                                            |
| bdb_log_buffer_size             | 32768                                                      |
| bdb_logdir                      |                                                            |
| bdb_max_lock                    | 10000                                                      |
| bdb_shared_data                 | OFF                                                        |
| bdb_tmpdir                      | /tmp/                                                      |
| binlog_cache_size               | 32768                                                      |
| 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/share/mysql/charsets/                                 |
| collation_connection            | latin1_swedish_ci                                          |
| collation_database              | latin1_swedish_ci                                          |
| collation_server                | latin1_swedish_ci                                          |
| completion_type                 | 0                                                          |
| concurrent_insert               | 1                                                          |
| connect_timeout                 | 5                                                          |
| datadir                         | /var/lib/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                                                          |
| keep_files_on_create            | OFF                                                        |
| engine_condition_pushdown       | OFF                                                        |
| expire_logs_days                | 0                                                          |
| flush                           | OFF                                                        |
| flush_time                      | 0                                                          |
| ft_boolean_syntax               | + -><()~*:""&|                                             |
| ft_max_word_len                 | 84                                                         |
| ft_min_word_len                 | 4                                                          |
| ft_query_expansion_limit        | 20                                                         |
| ft_stopword_file                | (built-in)                                                 |
| group_concat_max_len            | 1024                                                       |
| have_archive                    | NO                                                         |
| have_bdb                        | YES                                                        |
| have_blackhole_engine           | NO                                                         |
| have_compress                   | YES                                                        |
| have_crypt                      | YES                                                        |
| have_csv                        | NO                                                         |
| have_dynamic_loading            | YES                                                        |
| have_example_engine             | NO                                                         |
| have_federated_engine           | NO                                                         |
| have_geometry                   | YES                                                        |
| have_innodb                     | YES                                                        |
| have_isam                       | NO                                                         |
| have_merge_engine               | YES                                                        |
| have_ndbcluster                 | NO                                                         |
| have_openssl                    | DISABLED                                                   |
| have_ssl                        | DISABLED                                                   |
| have_query_cache                | YES                                                        |
| have_raid                       | NO                                                         |
| have_rtree_keys                 | YES                                                        |
| have_symlink                    | YES                                                        |
| hostname                        | localhost                                                  |
| init_connect                    |                                                            |
| init_file                       |                                                            |
| init_slave                      |                                                            |
| innodb_additional_mem_pool_size | 1048576                                                    |
| innodb_autoextend_increment     | 8                                                          |
| innodb_buffer_pool_awe_mem_mb   | 0                                                          |
| 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_arch_dir             |                                                            |
| innodb_log_archive              | 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_support_xa               | ON                                                         |
| innodb_sync_spin_loops          | 20                                                         |
| innodb_table_locks              | ON                                                         |
| innodb_thread_concurrency       | 8                                                          |
| innodb_thread_sleep_delay       | 10000                                                      |
| interactive_timeout             | 28800                                                      |
| join_buffer_size                | 131072                                                     |
| key_buffer_size                 | 8388600                                                    |
| key_cache_age_threshold         | 300                                                        |
| key_cache_block_size            | 1024                                                       |
| key_cache_division_limit        | 100                                                        |
| language                        | /usr/share/mysql/english/                                  |
| large_files_support             | ON                                                         |
| large_page_size                 | 0                                                          |
| large_pages                     | OFF                                                        |
| lc_time_names                   | en_US                                                      |
| license                         | GPL                                                        |
| local_infile                    | ON                                                         |
| locked_in_memory                | OFF                                                        |
| log                             | OFF                                                        |
| log_bin                         | OFF                                                        |
| log_bin_trust_function_creators | OFF                                                        |
| log_error                       |                                                            |
| log_queries_not_using_indexes   | OFF                                                        |
| log_slave_updates               | OFF                                                        |
| log_slow_queries                | OFF                                                        |
| log_warnings                    | 1                                                          |
| long_query_time                 | 10                                                         |
| low_priority_updates            | OFF                                                        |
| lower_case_file_system          | OFF                                                        |
| lower_case_table_names          | 0                                                          |
| max_allowed_packet              | 1048576                                                    |
| max_binlog_cache_size           | 4294967295                                                 |
| max_binlog_size                 | 1073741824                                                 |
| max_connect_errors              | 10                                                         |
| max_connections                 | 100                                                        |
| max_delayed_threads             | 20                                                         |
| max_error_count                 | 64                                                         |
| max_heap_table_size             | 16777216                                                   |
| max_insert_delayed_threads      | 20                                                         |
| max_join_size                   | 4294967295                                                 |
| max_length_for_sort_data        | 1024                                                       |
| max_prepared_stmt_count         | 16382                                                      |
| max_relay_log_size              | 0                                                          |
| max_seeks_for_key               | 4294967295                                                 |
| max_sort_length                 | 1024                                                       |
| max_sp_recursion_depth          | 0                                                          |
| max_tmp_tables                  | 32                                                         |
| max_user_connections            | 0                                                          |
| max_write_lock_count            | 4294967295                                                 |
| multi_range_count               | 256                                                        |
| myisam_data_pointer_size        | 6                                                          |
| myisam_max_sort_file_size       | 2147483647                                                 |
| myisam_recover_options          | OFF                                                        |
| myisam_repair_threads           | 1                                                          |
| myisam_sort_buffer_size         | 8388608                                                    |
| myisam_stats_method             | nulls_unequal                                              |
| net_buffer_length               | 16384                                                      |
| net_read_timeout                | 30                                                         |
| net_retry_count                 | 10                                                         |
| net_write_timeout               | 60                                                         |
| new                             | OFF                                                        |
| old_passwords                   | ON                                                         |
| open_files_limit                | 1024                                                       |
| optimizer_prune_level           | 1                                                          |
| optimizer_search_depth          | 62                                                         |
| pid_file                        | /var/run/mysqld/mysqld.pid                                 |
| port                            | 3306                                                       |
| preload_buffer_size             | 32768                                                      |
| profiling                       | OFF                                                        |
| profiling_history_size          | 15                                                         |
| protocol_version                | 10                                                         |
| query_alloc_block_size          | 8192                                                       |
| query_cache_limit               | 1048576                                                    |
| query_cache_min_res_unit        | 4096                                                       |
| query_cache_size                | 0                                                          |
| query_cache_type                | ON                                                         |
| query_cache_wlock_invalidate    | OFF                                                        |
| query_prealloc_size             | 8192                                                       |
| range_alloc_block_size          | 2048                                                       |
| read_buffer_size                | 131072                                                     |
| read_only                       | OFF                                                        |
| read_rnd_buffer_size            | 262144                                                     |
| relay_log_purge                 | ON                                                         |
| relay_log_space_limit           | 0                                                          |
| rpl_recovery_rank               | 0                                                          |
| secure_auth                     | OFF                                                        |
| secure_file_priv                |                                                            |
| server_id                       | 0                                                          |
| skip_external_locking           | ON                                                         |
| skip_networking                 | OFF                                                        |
| skip_show_database              | OFF                                                        |
| slave_compressed_protocol       | OFF                                                        |
| slave_load_tmpdir               | /tmp/                                                      |
| slave_net_timeout               | 3600                                                       |
| slave_skip_errors               | OFF                                                        |
| slave_transaction_retries       | 10                                                         |
| slow_launch_time                | 2                                                          |
| socket                          | /var/lib/mysql/mysql.sock                                  |
| sort_buffer_size                | 2097144                                                    |
| sql_big_selects                 | ON                                                         |
| sql_mode                        |                                                            |
| sql_notes                       | ON                                                         |
| 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                | CST                                                        |
| table_cache                     | 64                                                         |
| table_lock_wait_timeout         | 50                                                         |
| table_type                      | MyISAM                                                     |
| thread_cache_size               | 0                                                          |
| thread_stack                    | 196608                                                     |
| time_format                     | %H:%i:%s                                                   |
| time_zone                       | SYSTEM                                                     |
| timed_mutexes                   | OFF                                                        |
| tmp_table_size                  | 33554432                                                   |
| tmpdir                          | /tmp/                                                      |
| transaction_alloc_block_size    | 8192                                                       |
| transaction_prealloc_size       | 4096                                                       |
| tx_isolation                    | REPEATABLE-READ                                            |
| updatable_views_with_limit      | YES                                                        |
| version                         | 5.0.51a                                                    |
| version_bdb                     | Sleepycat Software: Berkeley DB 4.1.24: (January 11, 2008) |
| version_comment                 | Source distribution                                        |
| version_compile_machine         | i386                                                       |
| version_compile_os              | redhat-linux-gnu                                           |
| wait_timeout                    | 28800                                                      |
+---------------------------------+------------------------------------------------------------+
234 rows in set (0.00 sec)