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)

转载自：http://blog.csdn.net/jiangwei0910410003/article/details/24965087